Assure Tactical Sustainment

1. Logistics must enter the theatre of operations where infrastructure is concentrated, and so key sustainment nodes can be struck throughout operational depth.

2. Because supply is projected from known points of origin, it is susceptible to pattern-of-life analysis, enabling highly disruptive targeting.

3. Once forces are fixed in combat, the limited number of ground lines of communication to their positions makes them systemically vulnerable to isolation.

There are two processes involved in tactical sustainment: the flow of materiel forwards to resupply units; and the recovery of equipment and casualties rearwards. The principles driving tactical adaptation to ensure survivability of these functions are well established and well tested – dispersal, deception and convoys. Technology is transforming how these principles can be applied. For resupply, three technologies and approaches are critical.

1. The dispersion of caches throughout the rear support area can now be managed through digitised command and control (C2) and planning support tools to avoid concentrating supplies in logistics hubs.

2. The use of containers and mixed loads can create a uniformity and thus ambiguity to sustainment components that minimises the ability of the adversary to target the logistics structure efficiently.

3. The deliberate support to logistics elements from combat arms during last mile resupply to open windows for safe passage can enable safe delivery to the front. Given the constraints on how often this can be accomplished, it requires the accurate predictive push of materiel to be efficient.

Medical support is especially vulnerable. This is because of the electromagnetic signature of medical posts, combined with the decline in adherence to international humanitarian law as regards the protected status of hospitals. It is therefore necessary for medical support to:

1. Maximise the mobility of Role 2 hospitals by mounting their constituent parts on vehicles and maintaining modular capabilities.

2. Adapt tactics, techniques and procedures to enable surgery with intermittent relocation, to enable medical posts to continue to function in the indirect fire zone, ensuring damage-control resuscitation can be delivered within 60 minutes of injury.

3. Equipping and crewing Role 1 facilities to maximise the precision of triage to avoid saturating surgical capacity, bypass Role 2 for those who can be safely evacuated further to the rear on a longer timeline, and offer palliative care to those who cannot be saved.

4. Ensure that medical support has resilient C2 that can fully exploit the data necessary to coordinate dispersed operations.

Data is similarly critical to ensuring the survivability of repair and maintenance support:

1. The use of digital twins to conduct predictive maintenance on complex systems is a key tool for maximising the efficiency of forwards to support dispersed platforms.

2. For sophisticated components, platform modularity is critical in enabling sensors and other payloads to be swapped out, so that broken components can be repaired in the rear. For simple parts, additive manufacture can be used to minimise the number of unique spares that must be held at the rear of units and brought forwards.

3. For the repair sites themselves, deception is an increasingly important tool for improving survivability, as concealment is increasingly difficult.

Collectively, these measures can make a supply system robust, even under extensive surveillance. However, a sustainment system working in this way will still impose constraints on combat arms. It is therefore essential that the combat arms adjust their planning assumptions as regards tempo, the sustainable size of force packages, and the force protection they must offer to their service support arms if they are to sustain the fight.

Introduction

The cliché that while amateurs talk tactics, professionals talk logistics may be how militaries ought to function, but it is not reflective of peacetime practice. There is relatively little attention given to sustainment in either the British Army’s “Future Soldier” or the US Army’s “U.S. Army in Multi-Domain Operations”. As the Russian invasion of Ukraine has demonstrated, logistics appear to have played a limited role in the Kremlin’s professional planning, showing that the gap between policy aspirations and capability is far from being a uniquely Western conceptual oversight. Nevertheless, throughout history, logistics and sustainment have dictated the size of armies that can be fielded, their tempo, lethality, endurance and resilience. Furthermore, the threats that are reshaping tactics for combat arms units similarly create serious challenges for combat service support (CSS) elements. This paper seeks, therefore, to outline both the threats to CSS and how these risks can be mitigated through tactical and capability development. The questions the paper hopes to provoke – although not answer here – is how changes in sustainment operations must necessarily shape planning assumptions for the combat arms.

Sustainment is a broad doctrinal term encompassing logistics, medical support, engineering support, pay and personnel services, and maintenance. This paper concerns logistics and medical support forward of the corps: those functions that keep fighting formations able to operate, and which require regular transfers of materiel and personnel forwards and rearwards. The questions of theatre and operational sustainment at corps and above are beyond the scope of this paper, partly because they are largely a question of integrated air and missile defence and cyber defence, which are not solely relevant to sustainment. Nor is this paper concerned with tactics, techniques and procedures (TTPs) for tactical resupply by support companies inside fighting battalions, as this subject is specific to the particular sub-units being supported. The paper focuses on the divisional support area, protection of its functions, and the forward and rearward flow of materiel by close support sustainment units.

The paper is divided into four chapters. Chapter I outlines the threats to CSS elements, examining how the changing operating environment poses specific tactical problems for CSS. Chapter II examines how tactical and capability adaptation may solve some of these challenges for resupply of formations, focusing on the movement of materiel forwards in a largely proactively planned manner. Chapters III and IV examine how militaries may mitigate threats to sustainment activities that rely on rearward movement, largely imposed by the adversary: medical and maintenance support. The conclusion considers the impact of these considerations on combat arms, indicating areas for further study.

This paper has a broad evidence base. The assessment of threat systems is derived from: observation of deep strike capabilities and their kill chains employed during the Russian invasion of Ukraine; practical experimentation with a range of sensor systems and the associated signatures of CSS elements on exercises across NATO; and a review of literature on threat systems, mainly related to the impact on combat arms. The baseline for the potential threat is drawn from core planning assumptions for the sustainment footprint of existing formations. With regard to mitigations, the aim is to identify what a CSS footprint must look like to be survivable given the constraints of the task.

The paper’s conclusions are largely based on practical observation of sustainment operations, mapping timing and footprint, and interviews with CSS practitioners worldwide over several years. Interviews have also been conducted with dozens of figures in the field of medical sustainment, both individually and at conferences, workshops and exercises. Conclusions are also based on the bitter experience of one of the authors of observing the complications that arose around the sustainment of Ukraine’s armed forces, and the innovative solutions that were found. One of the authors is a senior practitioner, who draws on extensive experience from operations.

The paper’s methodology is, therefore, essentially an iterative mapping of dependencies. It is important to note that beyond theatre sustainment, military combat service support is, as B A Friedman observed, more of an art than a science. There are numerical inputs that generate the boundaries of possibility but, unlike in a civilian logistics system, the active attempt by an adversary to disrupt processes creates risk in the pursuit of efficiency. For this reason, the authors have sought to focus on the risk calculus that commanders will face, and the constraints the threat will place on their freedom of action.

I. The Emerging Threat Landscape

In June 2022 it would have been reasonable to assert that the Ukrainian military was being defeated. The enemy had amassed a 10:1 advantage in artillery, was achieving blanket saturation of the electromagnetic spectrum, and had shaped the battlefield to fix Ukrainian forces in killing areas. They were suffering an unsustainable attrition rate, while unable either to find Russian targets or to bring their guns in range to disrupt the Russian fires system. Then everything changed.

From late June, Ukrainian Guided Multiple Launch Rocket Systems (GMLRS) began to target Russian command-and-control (C2) nodes and logistics hubs. As stockpile after stockpile of ammunition was destroyed, Russian guns were starved of ammunition. The sudden need to disperse C2 alongside attrition of key electronic warfare platforms opened up seams in the electromagnetic spectrum. Over the course of two weeks, the Ukrainians started locating targets and striking back. The Russians saw their fires dominance evaporate, never to be fully regained. They adapted their logistics system, pulling stockpiles back beyond GMLRS range, but this limited the number of rounds their guns could reach, rendering it impossible to achieve the level of fires saturation demanded by their doctrine. In two weeks, the Russians not only lost fires superiority, but saw a whole way of war fade into obsolescence.

It would be reassuring to believe that the threat to logistics is a distinctly Russian problem. After all, it was GMLRS – fielded by several NATO countries – that disrupted the Russian logistics system. The Russians, meanwhile, have struggled to achieve a similar scale of disruption to Ukraine’s logistics infrastructure. This would be a hubristic level of complacency, however. An examination of how Ukrainian forces used satellite imagery to locate and map the Russian supply system, and the munitions necessary to strike its components, reveals that the technology is available and affordable even for non-state actors. Moreover, Western logistics practices are in many respects as vulnerable as Russian sustainment operations. NATO medical doctrine for warfighting is still fundamentally predicated on concentrating capacity in Role 2 and Role 3 field hospitals, with the Red Cross contributing to their protection. Ukrainian forces lost several such facilities, discovering that Russian EW-based targeting will not distinguish field hospitals from other nodes, and that the footprint of one of its Role 2 facilitiess fitted almost precisely within the lethal blast radius of a 122 mm high explosive round.

Any effective response to these challenges must be based on a realistic analysis of the threat. This paper begins with a summary of the “find and fires revolution”, as it applies to sustainment. There are three elements to this: ISR; connectivity; and precision strike. In turn, there follow three general problems for logisticians.

Large Footprints and Fixed Infrastructure

The volume of materiel consumed by a large military formation is immense. An Abrams main battle tank, for example, consumes approximately 1.86 gallons of fuel per mile. A squadron traversing 10 miles of terrain could easily consume 260 gallons of fuel, not counting the fuel required for their supporting vehicles. The volumes necessary to sustain an army require the exploitation of large-scale commercial infrastructure before fuel and supplies can be broken down into deliveries to the front. Sustainment operations are therefore critically dependent on ports, terminals, rail infrastructure, storage tanks, and depots – large, fixed targets that cannot be moved rapidly.

The concept of dispersion, viable for tactical formations, is only partially realisable for sustainment operations. This is because the greater the distance that logistics elements need to travel to resupply forces, the less efficient the logistics operation, since a greater proportion of the organisation’s resource must be used to resupply and sustain itself. In Afghanistan, where logistics infrastructure was largely uncontested, sustainment operations absorbed up to half of the force. This is not a historically unusual proportion. Rapid expansion of a logistics operation therefore comes at the expense of the efficiency of the force. Moreover, the greater the level of dispersion of logistics elements, which for reasons of efficiency are necessarily lightly armed and armoured, the greater the force protection requirement, drawing combat arms away from combat tasks. Furthermore, sustainment must flow through civilian infrastructure, such as ports, that is optimised for efficiency in peace and therefore concentrated. After this point they may begin to disperse, but they enter theatre concentrated.

The result is that logistics and sustainment must concentrate at the operational level in large, fixed installations that are identifiable to the enemy and which often constitute single points of failure. In the Falklands campaign, a strike on the logistics hub at Ajax Bay would have immobilised much of the British force. The runway at Ascension Island constituted another potential single point of failure in the ability to maintain momentum. In Russia’s invasion of Ukraine, although there are multiple options for supplying the various fronts, Crimea, which is vital ground, is essentially dependent on two railways for resupply, one of which depends on a single prestige piece of infrastructure: the Kerch Bridge.

Historically, many logistics sites were protected by two factors. First, the enemy lacked sufficiently accurate weapons to reliably destroy these targets. The US, for example, had to fly hundreds of sorties to be able to reliably damage bridges before the introduction of precision guided munitions, and even after laser designation increased accuracy, the threat to aircraft from surface-to-air missiles made such targets high risk. The second factor was the number of munitions that needed to be brought to bear to have a decisive effect. Precision munitions were expensive, while the separation of stores by berms across a depot would mean that a large number of munitions would need to be committed to destroy materiel where it was concentrated. It is also worth noting that some classes of sustainment infrastructure – notably hospitals – have protected status and ought not to be targeted.

These factors no longer hold. The proliferation of cruise missile technology means that strikes against critical logistical infrastructure can be sustained without exposing crews to risk. Moreover, the maturation of cheap one-way-attack munitions, capable of damaging soft targets and striking with considerable precision, means that it is now possible to precisely strike a large volume of targets across a logistics depot, destroying stores in place. The destruction by Russian forces of several Ukrainian ammunition dumps with thermite grenades (prior to the full-scale Russian invasion) and the detonation of a Syrian Army ammunition dump at a stadium in Deir ez-Zor with improvised one-way-attack munitions demonstrate the scale of effect that is achievable by these means. The presumption of protected status, moreover, is no longer honoured by many states, rendering these facilities highly vulnerable.

At higher echelon the impact of these trends is relatively straightforward. First, depots are being moved into greater depth to increase the cost of the munitions that can reach them and thereby reduce the number of strikes that are possible. This then allows for the concentration of defensive systems. However, supplies must subsequently traverse a greater area, and satisfactory solutions for the protection of sustainment capabilities in the intervening space have not yet been identified.

Pattern of Life

Closer to the Forward Line of Own Troops (FLOT), the challenge is that sustainment operations create highly predicable and detectable patterns of life. Vehicles must drive through fuelling points and casualties have to be drawn back to medical facilities. Refuelling and casualty movements both require dynamic planning and thus communication, such that the medical facilities and sustainment points acquire pronounced and distinctive electromagnetic signatures.

Historically, unless a signature was maintained for a sustained period, incidental exposure provided limited opportunity to systematically map CSS elements in the deep. Today, however, Ground Moving Target Indication, space-based electromagnetic surveying and other wide-area collection systems enable the sustained observation of patterns of life throughout operational depth, including the tracking of unique signatures. When combined with modern analytical tools, the patterns that emerge over time become highly revealing. For example, if vehicles routinely pause outside a particular building when rotating to and from the front, they immediately become a point of interest, to be placed under close analysis. If synthetic aperture radar imagery can be cued to coincide with a vehicle stopping, it may become possible to confirm that it is a fuelling point. Russian strikes on medical facilities in Syria are a useful case in point. The persistent communication from these facilities, and the presence of cellular phones associated with fighters, made even subterranean facilities distinctive. For Russia, lacking concerns about international law, these facilities became targets.

The handover of supplies to units in motion must be based on battle drills and standard operating procedures. The selection and communication of cache points, the deconfliction of movement through the rear, and the confirmation of time of handover will all follow pre-agreed procedures that will be replicated. Sustainment, unlike many tactical actions, is a constant task and so there is a consistent pattern of life generated by a force’s tactics, techniques and procedures. These are not only detectable – increasingly so over time – but once a point has been confirmed it becomes possible to track vehicles moving to and from locations to build up a map of logistics nodes, so that the exposure of one point can contaminate others.

The stand-off sensors that enable this kind of observation – satellites, radar, long-range UAVs and other capabilities – are persistent and survivable. For units conducting tactical actions, the use of electronic warfare and other measures can disrupt enemy kill chains and intelligence collection for limited periods to create windows of opportunity for manoeuvre. But it is not realistic to achieve widespread denial of these capabilities over a sustained period and an expansive area. Consequently, the burden of adaptation falls to the sustainment elements

Finally, the more that is done to protect sustainment elements, especially force protection engineering, the greater the signature of the activity and the easier it is to track and map. For example, it was possible just using commercial satellites to track the end-to-end transfer of ammunition for Russia from North Korea to the Ukraine front by observing the loading, unloading and preparations for receipt of shipping containers. The expansion of berms ahead of the arrival of these munitions was a clear indicator of where materiel would be moved, even before it was shipped. With access to real-time ISR – rather than commercial satellites with longer latency between collection and dissemination – it would be possible to track the movement forwards from these dumps and thereby establish the placement of caches or the location of batteries.

The Predictability of Ground Lines of Communication

Manoeuvre forces have a range of options to prevent them from being located with a high level of accuracy or, worse still, anticipated. Dispersion and the exploitation of multiple axes or unusual approaches to targets can allow them to maintain a high level of ambiguity as to their movements and dispositions while out of contact. For sustainment elements, supporting dispersed forces reduces efficiency, but is achievable. Once combat elements become engaged with the enemy, however, two important things occur. First, sustainment demand spikes, as combat forces use their ammunition at a much greater rate and begin to require evacuation of damaged vehicles and injured and dead personnel. Second, combat forces become fixed and the options for the routes by which resupply can occur become significantly constrained, especially if the contact occurs on vital ground. Resupply may be via only one or two ground lines of communication (GLOCs) to reach the fighting units. Moreover, as artillery targets rotating units or resupply convoys, the available GLOCs are degraded or destroyed, with bridges especially susceptible. Temporary bridging can alleviate this problem somewhat, but between the weight limits and damage to the roads, it is common for traffic to only be able to move in one direction over these points. This risks creating traffic jams, and so careful sequencing of forward and return traffic becomes critical. This planning requirement further constrains sustainment troops’ ability to manoeuvre, because they must deliver a significant proportion of materiel and recover casualties within specified timelines, while also having set windows of opportunity within which they can do so along GLOCs.

The threat to contested GLOCs has been exacerbated by UAVs. Penetrating the FLOT, UAVs will routinely seek to maintain observation over GLOCs and thereby direct artillery fire onto sustainment troops while they move. This dynamic has occurred repeatedly throughout Russia’s invasion of Ukraine, such that in some instances Ukraine has lost more personnel during troop rotations than it has in contact. The planning challenges created by the sustainment of Severodonetsk, Bakhmut and Avdiivka are instructive. In these instances, two GLOCs were preserved but were held under artillery fire. The interdiction of Russian sustainment operations over the bridges in support of Kherson are similarly illustrative of how a force can be disproportionately attrited by fixing its combat power to expose its logistics elements and then using fires to render the position unsustainable.

Defending sustainment assets once fixed in combat can be achieved. Sanitising the airspace above GLOCs for a period can be delivered by electromagnetic warfare troops and air defence. The use of fires to suppress enemy artillery during a resupply can also reduce the threat. Alternatively, engineers can work to expand the quality of the route, or the number of paths that can be taken. In extremis, logistics can be carried out by vehicles with greater off-road mobility, whether amphibious or tracked, to maintain a diversity of avenues of approach. For small and urgent deliveries, unmanned aircraft systems may be able to shuttle material forwards. The problem with all these methods is that they lead to combat arms who are in contact, diverting resources to protect resupply. This in turn increases the sustainment requirements of the force. Even increasing the mobility of the sustainment force through different vehicles necessarily comes with an increase in cost and complexity, and expands their organic support requirements. These all reduce the efficiency of the fighting force.

A final complication is the handover of materiel to troops. If the support to forces in contact is conducted within a constrained window of time, determined by the period when counterbattery fire and air defence can lift the threat, it encourages the maximum volume of materiel to be pushed in the smallest number of vehicles possible. The combined arms enablement of the resupply, however, means that the enemy will know what is happening. Once the supplies have arrived at the battle area, they must then be distributed to dispersed fighting elements. First, there is the risk of the supplies being struck once unloaded. Second, there is the risk that if a support element moves supplies from the unloading point to the fighting positions it will be traceable – enemy ISR would have been tipped off about the need to focus by the counterbattery fire – and so will reveal the fighting positions and separate them from the decoy fighting positions that forces are increasingly having to use to remain survivable.

Collectively, therefore, the find and fires revolution risks making supply of forces costly and complicated by holding fixed logistical infrastructure at sustained risk, by unpicking the supply nodes through pattern-of-life analysis in the deep using stand-off sensors, and by contesting the GLOCs to fighting units. The result of this is to diminish the ability of a force to achieve operational tempo and, by constraining the supplies that can be built up, limit the depth that units can plan to threaten and thereby limit the cognitive risk felt by the enemy. If units can only build up the ammunition, fuel and other supplies to punch a limited distance into enemy terrain before pausing, it becomes easier for the enemy to manage the release and commitment of reserves to ensure that offensive operations must always be against a deliberate, rather than a hasty, defence.

II. Adapting Resupply to Sustain the Force

There are, in very simple terms, two kinds of sustainment activity. The first is resupply – pushing materiel forwards; the second is recovery – pulling resources backwards, for example, maintenance and medical capabilities. This chapter considers the process by which materiel is moved forwards, while Chapters III and IV consider recovery. Having examined the factors that expose sustainment operations to distinct threats on the future battlefield, several conclusions can be drawn about how combat service support elements will need to adapt, and where adaptation will impose additional demands on the wider force.

The principles of protection described in this chapter are not new. Dispersion, deception and convoys are techniques that have been used for centuries. However, these concepts can now be applied in particularly important ways because of emerging technologies. This chapter therefore considers the relationship between technology and emerging tactics to address an evolving threat.

Randomised Dispersed Storage

Consider a warehouse. Traditionally, it has comprised rows of shelves on which objects are placed in a systematic order. Books, for example, might be laid out alphabetically, or boxes given serial numbers, to be stacked in sequence. Each shelf stack would have a designation. Goods that were regularly requested would be stacked closest to the door, and those objects least regularly requested stacked further from the entrance, to maximise efficiency. Such a system allowed a human logistician, who could not remember where an object was in the warehouse, to look up its location, quickly proceed to the relevant area and then move along the shelves until arriving at the correct item. Someone who had never visited the warehouse before could find the items they needed.

With their network of depots and storage dumps, divisional and brigade support areas follow similar patterns – orderly sites where paper-based tables allow supply personnel to enter and retrieve specific loads. Such a system means that when a spare part arrives from a higher echelon, as long as it is allocated an appropriate serial number it can be inserted in a location where it can rapidly be found. In NATO militaries, this system has evolved to work in support of a pull logistics system, whereby units flag their requirements and only the requested items are retrieved from their storage locations, reducing waste.

The layout of modern warehouses is changing, however. In a warehouse with a robotic retrieval system, or “smart warehouse”, it is not uncommon for the storage of items to be random. Books might be stored next to toasters and shower gel, with no particular logic other than that dissimilar items are co-located. The reasons for this are simple. For a computer, when an item is placed in the warehouse, its coordinates in three dimensions can be retained as a small data entry and remembered. Unlike the human operator there is no need for a robot to work towards an object by following a building–stack–shelf–location sequence, it can simply go to the coordinates associated with the item. Dissimilar storage reduces the likelihood of mistakes (for example, through a calibration error of a robotic arm). An error is much more likely to be detected if, in attempting to pick up a book, it finds itself clasping a shovel (as opposed to a different book). Even if the machine does not detect the error, a supervisor is more likely to notice. Randomised placement, while reducing the risk of localisation errors for robotic retrieval systems, is not space efficient, so there is much effort put into refining localisation methodologies in civilian logistics. Since the military will continue to retrieve items using humans, however, localisation does not need to be as precise.

The relevance of this to militaries is not that robotics can replace humans in logistics, but rather that the distribution of materiel across the battlespace need not see the concentration of like materials at centralised locations. Militaries have used GPS tags on shipping containers to assist in retrieving the appropriate boxes for some time. The problem with this is obviously that the boxes broadcast their location and that there is a high risk of GPS disruption. The digitised warehouses, however, hold the location data centrally, based on logging where it was placed. This appears to be a more viable approach, although periodic backups are necessary to avoid corruption of the database. The result is that today it is reasonable to have materiel scattered broadly in small caches all over the rear area in such a manner as to massively complicate tracking and targeting and reduce the efficiency of strikes.

One historical downside to dispersing logistics is the planning complications it introduces of moving materiel from depots to units. With a paper-based planning process creating orders, the need to coordinate movement to a large number of unpredictable dispersed locations every time there is the requirement to resupply a unit would take a great deal of time. It would also create a range of challenges as regards route deconfliction, and a need to coordinate laterally between different logistics units that would entail much communication.

The difference today is the ubiquity of smart planning tools. Uber Eats is perhaps the most immediately comprehensible civilian corollary. Uber Eats is premised upon a situation where a recipient will call for supply from a position that was not previously known, for materiel from a location that was not previously known, and the application must calculate the most appropriate carrier given the timing and location of both parties. Moreover, it must coordinate many of these interactions simultaneously. Uber Eats has the advantage of a highly detailed map, terrain that degrades very slowly, and ubiquitous connectivity. Nevertheless, ticketing systems could make it feasible to push jobs to elements with intermittent connectivity. The military today has the capacity to map terrain rapidly using space-based observation. Route planning that accounts for damage is harder to automate, but the process of manually updating this information is fundamentally comparable to the burden of feeding this data into staff planning. A range of technologies today, therefore, allow for storage of materiel to be effectively dispersed throughout the battle area without having a disproportionately negative impact on efficiency. Beyond the key points of theatre entry where civilian logistics anchor logistics, therefore, it becomes possible to break up the concentrated supply areas in the divisional support area, eliminating high pay-off targets.

Ambiguous Loads

Safety in the carriage of ammunition and fuel is important. Incidents such as that aboard RFA have underscored the sound injunction to separate the carriage of personnel and munitions. This has since been extended to an aversion to mixing loads of most kinds in peacetime. Thus, militaries often field specialist fuel bowsers that have a distinct signature. This helps logistics in peacetime because it means the bowsers can meet safety standards and have greater freedom to drive on civilian roads. There is also an efficiency to the concentration of materiel in transit. For example, a box of ammunition will stack neatly with other boxes of ammunition because they have the same dimensions, and the tracking of materiel is also simpler if each container contains a specific type of item. Thus, a round of ammunition will sit in a box of ammunition, which will sit on a pallet of ammunition within a container shipment of ammunition, for which there will be a clear set of rules governing the transport, tracking and security of the load.

The efficiency of this approach must contend with the need to break down loads in order to actually resupply units. Few tactical units, for example, require a shipping container’s worth of ammunition. A pallet is much more manageable. Unhelpfully, they also require food, water and spares that do not pack neatly, along with many other consumables. Generally, the need to concentrate the shipping containers to be able to draw from multiple different kinds of stores is done at relatively high echelon because of the concentration of containers. Nevertheless, loads tend to remain separated, with a supply convoy having different loads on different vehicles. Resupply convoys will then move to handover points, either with the logistics unit supporting the lower echelon, or once the operation shifts from formation sustainment to unit resupply, the convoy will usually conduct a circuit, handing over several pallets from each vehicle to a receiving group from the unit, to be broken up according to the disposition of the unit and thereafter distributed to the various fighting elements. This approach is noteworthy for its simplicity and efficiency.

It is also increasingly vulnerable. It necessarily creates a series of interlinked circles of continuous movement, from known storage hubs to identifiable handover points, and the movement from these points can be traced forward to identify fighting positions. Moreover, the separation and distinctness of loads produces some very particular vulnerabilities. The UK’s 1 Aviation Brigade, for example, fielded eight fuel bowsers as its entire fuel capability until recently. Targeting these could potentially have grounded the brigade. Their movement from the main brigade support area could also indicate the establishment of a forward arming and refuelling point, setting up the conditions for strikes during refuelling. Measures have since been taken to address this and other vulnerabilities. Nevertheless, the example is instructive.

To break the pattern-of-life vulnerability generated by the existing model and reduce the size of logistical resupply convoys, it is necessary to adopt two measures. The first is to increase the ambiguity of loads by pulling shipping containers further forward in the battlespace. The second is to shift to mixed loads, not of people and ammunition, but of different kinds of stores. Clearly, when containers are shipped into the theatre, efficiency will drive them to be concentrated, as is currently the case. However, at the theatre sustainment level, it becomes desirable to unpack these containers and pack containers with unit-relevant caches comprising mixed loads. Some loads, such as fuel, cannot be readily mixed, but should still be pumped into bladders within containers, thereby rendering the contents of any given shipment ambiguous.

Medical stores and facilities have traditionally been visibly distinct, partly as medical elements are specifically protected under international humanitarian law (IHL) if they hold to their duties of neutrality and do not, for example, engage in moving ammunition or other lethal supplies. Critically, this protection has been shown to be ineffective in many current conflicts, with hospitals now becoming specific targets. It may therefore be reasonable, or indeed necessary, to hide medical stores and even units in the plain sight of general supplies. Rendering medical capabilities indistinguishable from other stores, rather than actually mixing loads with them, is compatible with IHL, although it means that enemies who strike these facilities have the defence that it was not possible to discriminate between them and legitimate targets. This approach may be highly context dependent, as some adversaries may show greater respect for non-combatant status than Russia.

The exact contents of a container cache depends entirely on the formation being supported and the planning assumptions of its levels of consumption. However, to use straw man figures to illustrate the process, in intense periods of fighting an infanteer can expect to need 616 rounds of 5.56 mm ammunition per day, assuming a carriage of 10 magazines, plus one in the rifle, and one full replenishment. Often they carry fewer, but this is the upper limit. If they were carrying fewer, many would use the saved weight to carry additional rounds for machine guns or other support weapons. Thus, a company plus attachments, roughly 150 people, will need approximately 92,400 5.56 mm rounds or equivalents per day in intense fighting. An ammunition box holds approximately 1,200 rounds of 5.56 mm. A standard pallet measuring 100 cm x 120 cm can hold approximately 21 boxes, so that four pallets can carry 100,800 rounds. Four pallets can also carry enough 24-hour ration packs for an equivalent number of troops. Thus, packed with the rations over the ammunitions, food and ammunition for a company for a day can fit into a 10-ft shipping container. A standard lorry could either carry a second 10-ft container for other kinds of stores, like batteries and water, or a single 20-ft shipping container, with all stores in the same container.

Rather than a handover point, there could be a process whereby mission caches are carried from the operational hub in small packets of vehicles and the containers dropped in the rear of a unit. The location of the drop and the contents of the container is uploaded to the logistics system. When it comes time for the unit to retrieve its supplies, its close support logistics element raises a ticket with the logistics C2 system and is assigned a location, or several options, where the requested stores can be found. They can then retrieve the pallets, leaving the container, while informing the logistics C2 system of what was taken.

In the first instance, this may not sound very different in its implications to the current process. Over a relatively short period of time, however, the effect is to distribute many containers across the rear area, some of which are empty, while others remain full, some of which contain fuel and others not, and some of which contain specialist loads, while others contain standard stores. It rapidly becomes highly ambiguous for the adversary to know where anything is, or what any pattern might be. Containers can, of course, be periodically retrieved. Or one of the containers whose contents have not been depleted may be moved further forward as the force advances. The result, however, is to break any consistent pattern as to where close support logistics elements go, and thus mitigate the threat from pattern-of-life analysis.

Planned Predictive Push and Last Mile Resupply

The current logistics approach in most NATO militaries is primarily a pull logistics system at tactical echelons. Units call for what they need, and the logisticians work out how to get it to them. Logisticians may well pre-position stores that they anticipate being needed, but this is usually driven by the manoeuvre formations’ planning process, with the logistics plan intended to enable the scheme of manoeuvre. The logisticians work under the manoeuvre forces for several reasons, but an important one is that the manoeuvre forces take the highest burden of the risk, and therefore the logistics troops are combat service support. Ultimately, UK doctrine stipulates that “sustainment is a means to an end. Sustainment should always support the mission”.

The future operating environment is one in which targeting logistics is likely to be systematic among advanced militaries, because of the disproportionate impact it has on the capacity of combat forces to operate. Moreover, rather than logistics troops being a high pay-off target of opportunity, militaries increasingly have the means to reach over one another and strike the tail. The result is that logisticians must be significantly more proactive in planning their movements. Consequently, movement will often be discontinuous from the wider scheme of manoeuvre. The caching of materiel rather than its handover is a good example of something that facilitates this transition. The logistics planners may also require the support of combat arms in some instances, to shape conditions for access. This is especially true of electronic warfare troops and air defence.

A critical enabler for moving to an efficient push model is data. If the distance between centralised supply depots and the front is extending, then the risk is that critical materiel cannot reach units in time. This requires the right volumes of the right things to be pushed forwards in anticipation of need. Historically, push systems have been robust but inefficient. However, accurate predictive modelling can drive efficiency, drawing on data on actual consumption under various conditions. Since the caches are containerised, there is also less of a cost if the materiel is not used. It can be left in the container and recovered later, although it may be necessary to deny some critical materiel if it is at risk of being overrun.

The combined arms element of the logistics plan becomes especially relevant in last mile resupply, from the caches to the sub-units. This will inevitably require movement along exposed GLOCs. The breakdown of company supplies to roughly four tactical vehicles allows for a small footprint to move rapidly along a GLOC. This ensures that only the most responsive fires are likely to prove a threat. UAVs, however, either directing artillery or striking themselves, are a major threat during this phase. The most effective means of reducing this threat are air defence engagements against larger UAVs and electronic protection against ISR and smaller strike UAVs. Navigational jamming is especially important, as even if an adversary gets a UAV over the convoy, it significantly complicates the accuracy of engagements. Disruption of navigation is not just applied against the UAV but also against the launcher, further corrupting the enemy kill chain. Jamming of control frequencies, meanwhile, is important for protection against terminally guided UAVs.

Air defence assets are scarce, while electronic warfare capabilities risk causing considerable disruption to friendly C2 if they are not deconflicted with friendly activity. It is therefore very important that the mechanisms exist for logistics units to call upon and receive this support from the combat arms, which in turn requires the planning process to be responsive in processing these requests and applying appropriate control measures and deconfliction procedures. Support engineering, whether for mobility support or force protection, is another function that logisticians may need to call upon to expand their options. Here the deconfliction requirement is in capacity, rather than fratricide.

A further critical function is logistical reconnaissance. This enables proactive push logistics by identifying areas that are appropriate for caches, and enabling the preparation of optimal sites for receipt of caches. For example, if pushing into an industrial area, warehouses or other facilities with large spaces with overhead protection offer a great opportunity to disguise and conceal dispersed caches. Route access, vehicle clearances and what to do with what might already be in the warehouses all require information to plan.

Planning for the positioning of caches also provides an anticipated laydown that can be used by the joint force to plan protection of logistical supplies. The requirement here is not that each cache be allocated a cordon of troops, which would be prohibitively burdensome. Nevertheless, it does make sense for shipping containers containing ammunition to be kept under observation. This could be achieved by remotely rigging a camera and running the feed from it via cable to a hide position. Locking the container can also create a barrier to civilians tampering with the contents. Simply having troops with overwatch of the site, rather than ringing it, is sufficient in many environments. Of course, even having troops in overwatch would be onerous if it is a dedicated task. However, on a battlefield where reserves need to remain dispersed, logistical reconnaissance proves to be the basis to plan hiding positions for reserve troops, such that there is coincidental force protection for stores without driving concentration. A further function of this reconnaissance is that it provides information to identify points to which materiel might be recovered. Via these means, therefore, using digitised C2 to disperse logistics hubs, moving ambiguous loads, and taking a combined arms approach to resupply, it becomes possible to resupply the force.

III. Medical Support

Although some medical supplies require special handling, the provision of medical logistics forwards can be made robust through the wider techniques discussed in Chapter II. Medical support, however, entails a greater reverse logistical component; significant effort is expended treating casualties and then bringing them away from the frontline. Also, the adversary often sets the level of demand, at a time and location of choosing. This chapter considers necessary adaptations to medical support on the future battlefield. It focuses on discrete medical capabilities – rather than on those intrinsic to the fighting units – and looks in particular at additional pre-hospital care teams and forward Role 2 surgical capabilities, as these are likely to be most impacted by recent developments.

Prioritising Mobility in Medical Capability

The transparent battlefield will always expose a medical treatment facility (MTF). Even if the MTF itself can be hidden (for example, underground), the casualties flowing to and from it will always set a distinctive pattern; for example, researchers were able to map the first surge in Covid-19 medical attendances in Wuhan using satellite imagery of hospital car parks. They will also be highly visible in the electromagnetic spectrum, because of the C2 required to facilitate casualty movement and reach-back for specialist advice.

Loss of an MTF will hugely complicate the demands placed on other support elements and will directly affect the psyche of the fighting force and the population at home, putting a state’s political will to the test. This combination of visibility and value makes healthcare a logical target. IHL aspired to mitigate this by making medical units non-combatant – taking them out of the fight and protecting them, in return for their duty to treat any and all who need it. Sadly, this protection is ineffective. Attacks on MTFs are commonplace; the WHO recorded 806 in 18 countries in the first 10 months of 2023. In some conflicts, MTF targeting appears to be state policy – most notably Syria, where 274 government-attributed attacks affected hospitals, compared with only one on a school in the same timeframe. Attacks on military medical facilities are rarely publicised in Ukraine, for reasons of operational security, but are nevertheless frequent.

Given that hospitals will be found and targeted, the enemy imposes a critical decision on planners. Should they place medical facilities beyond the range of attack (and/or harden them to survive), or simply make them very difficult to target? With long-range precision fires, a static MTF can never be close enough to deliver life-saving interventions early and remain safe from attack, unless it is also protected. This concept is not new – underground hospitals were used during the First World War and are commonplace in parts of Syria and Ukraine. However, this brings additional constraints, dramatically reducing the number of feasible deployment sites and fixing the facility. Critically, while this approach protects the hospital, the rest of the network assumes proportionally greater risk; even if varying routes and timings, ambulances and resupply always end up at the same place.

The US is already moving away from fixed canvas or opportunistic hard-standing for C2 nodes, “focus(ing) on mobility as the chief mechanism for survivability”. For Role 2 MTFs to achieve this level of mobility, they must either be smaller, limiting capacity, or subdivided, limiting efficiency. The size of vehicle required to enable truly mobile medical provision has historically been considered unfeasible. But with Boxer command vehicles (7.93 m long and 3 m wide) assessed as survivable on the battlefield, that assumption is no longer tenable. The total size (and hence capacity) of an MTF still presents challenges. A common Role 2 configuration contains: two resuscitation beds; one operating table; two intensive care beds; a ward area (up to 12 beds); as well as x-ray and laboratory equipment, and blood fridges. That significant footprint actually works in favour of the distributed model. Role 2s usually experience relatively little clinical activity. Mass is only required when demand for life-saving damage control resuscitation (DCR) peaks. A modular approach would allow smaller, dispersed units (each containing, for example, an operating table, an intensive care bed and a blood fridge) to move closer to likely points of demand. Modules would only come together and reconstitute mass when absolutely needed, for exactly as long as needed.

Highly mobile MTFs bring considerable advantages: they can move whenever there is a risk that they have been targeted; RVs with resupply or evacuation platforms can be different every time; they can easily be redeployed if reinforcement is needed elsewhere; they can operate far closer to the point of wounding, potentially increasing the pool of salvageable patients that can be reached; they can set up in a far wider range of locations; and they can always choose to fix in an ideal location (even a distant, underground, protected one) if that suits the operation, whereas a static hospital can never choose to move in anything approaching a relevant timeframe.

Mobility also brings considerable challenges, most notably the significant changes to TTPs that will be required to cope with movement and their reduced capacity, and the vast increase in coordination (and so communication) and logistical support to manage many moving parts. Perhaps most important, if it fails to move in time, a mobile MTF is much more likely to be destroyed. While dispersal will reduce the likelihood of a strike being mission-killing, it is unlikely to be hardened to the same degree as a static facility, and so there will be losses.

Adapting TTPs to Enable Mobility

Surgery cannot yet take place in the face of vibration and sudden movements. While a static facility can operate continuously, a mobile unit can only deliver care when stationary. That said, Defence Medical Services surgeons have confirmed that most DCR procedures could be tactically paused for 10 minutes, given five minutes’ notice to move, allowing doctors to “cross-clamp” major blood vessels and then secure safety harnesses. This would allow a targeted vehicle to rapidly relocate, then apply the brakes and continue the procedure. Clearly this would not meet the NHS standard of care – and will likely result in worse outcomes for some than if the operation was never interrupted – but on a battlefield, it offers the best balance of urgency and safety.

Treatment would need to be reconceptualised in tactical bounds, interspersed by very short-notice moves. This applies equally to tactical medical evacuation (MEDEVAC). In Ukraine, enemy air defence coverage means that patients must be transported by ground vehicles; terrain (and the time needed to cross it) becomes critical in determining what treatments can be undertaken and when. Delivery of care in ambulances moving on roads is difficult; over rough terrain it is impossible. The holy grail of “in-transit care”, which brought such improvements in survival in Afghanistan and Iraq, will at best be replaced with “interrupted transit care”.

Timelines must also be re-evaluated. For logistical enablers, MEDEVAC will compete with the forward movement of ammunition. Commanders will prioritise the latter, as ammunition scarcity will increase casualties through reduced suppression of the enemy, perhaps even leading to defeat of the force, whereas delayed evacuation of casualties will only impact the minority of salvageable wounded. This calculus, along with the practicalities of movement under fire, has at times pushed casualty evacuation in Ukraine to over 15 hours. While enhancements to Role 1 facilities and the continuing focus on prolonged field care will mitigate this problem somewhat, fundamentally, the force must either accept clearly preventable deaths, or move advanced care forward.

Risking scarce medical expertise forwards will demand clarity on who these personnel are there to care for. The human body is remarkably robust and survives most injuries, even if care is significantly delayed – 99.2% of all UK armed forces personnel treated in the hospital at Camp Bastion survived. Sadly, some will die, regardless of the proximity and capability of medical services, as their injuries are simply too severe to recover from. Of all UK service personnel killed in action in Afghanistan, 87% died before reaching hospital – two-thirds within 10 minutes of injury. Even with the current pace of innovation, it is unlikely this figure will improve significantly in the foreseeable future, as access to the necessary advanced care inside that timeframe will rarely be feasible while in contact. The patients who will benefit from advanced medical care in this environment are those who will die if untreated but are “salvageable” given the right level of care (DCR) in the right timeframe. These patients hide among the 35% who were not killed immediately, but died in what is currently the pre-hospital stage.

How long do they have to reach DCR? There is a 33% survival benefit if surgery is accessible within an hour, but the ideal timeframe is probably shorter; giving blood only improves survival within 36 minutes of injury. Experienced military pre-hospital doctors did not believe they could keep salvageable patients alive for two hours pending surgery. The inescapable conclusion is that salvageable patients need advanced pre-hospital care surgery, well within the first hour, not the two proposed in NATO doctrine when the medical system is under strain.

▲ Figure 1: Analysis of Time to Death for Those Killed in Action. Source: Stacey Webster et al., “Killed in Action (KIA): An Analysis of Military Personnel Who Died of Their Injuries Before Reaching a Definitive Medical Treatment Facility in Afghanistan”, BMJ Military Health (Vol. 167, 2021), pp. 84–88. Reproduced with permission.

Each DCR vehicle would probably only have space for one surgeon, an assistant and an anaesthetic practitioner. Single-surgeon teams always run the risk that they are the “wrong” specialist for a given problem; for example, an orthopaedic (limb) surgeon faced with an abdominal wound or a general (abdominal) surgeon treating an amputation of a limb could not typically deal with the injury completely within their normal scope of practice. But in Defence, both can be made competent in the immediate control of any bleeding, even if it is not in their specialist area. The “clamshell thoracotomy”, taught to all UK pre-hospital doctors (who are typically not surgeons at all) is one such technique. With minimal equipment, the practitioner opens the patient’s chest to access the heart and main blood vessels. Once the bleeding is controlled – on average 4.6 minutes later – they have bought some time for rendezvous with the ideal team to continue.

These modules could operate in “pods”, with multiple surgical vehicles supported by a mobile intensive care ward (which could also undertake MEDEVAC). If patients need a larger or reconfigured team, the vehicles could come together for a short period, reorganise to provide the interventions needed and then disperse again. Fresh modules can be en route (bringing critical resupply) while full modules can MEDEVAC back to the next echelon of care. This would also build resilience in the event that a vehicle is hit; the remaining surgical and critical care capability will still endure, ready to be fully regenerated by vehicles moving from another area to support, or battle casualty replacements arriving. In the event of mass casualty incidents (MCI), multiple pods could converge on the affected areas, boosting medical cover at critical moments in a way that static facilities never could.

▲ Figure 2: Patient Movement Towards Modular vs Traditional Role 2. Source: Author generated.

Containerising these modules allows them to be delivered by any platform “fitted for, rather than with”, enabling far greater transport flexibility. If an operation required them to take up a static position, they could be placed into dug-out scrapes or underground, dramatically increasing their protection. For concealment and deception they could be sited anywhere a container would not look out of place, such as a supermarket supply entrance, ready to be picked up and redeployed when needed. Two-operating table collapsible versions of such modules exist (within standard 6-m ISO-container dimensions). While these cannot contain patients while “collapsed”, they illustrate the feasibility of the concept.

The natural state of the MTF should be dispersed over a kilometre or more, operating within 30 minutes of the units for which it is providing support, and either in motion or moving frequently (and able to change location immediately). If static, it should be hidden and/or protected. It can be in the vicinity of defences and enablers (excavators and so on), but dispersed enough to not draw fire.

Precision Triage, Treatment and Palliative Care

This construct only provides the care necessary to save lives that would otherwise be lost. Most medical care falls outside that definition. Disease and non-battle injury will continue to be the predominant source of medical work (and thus logistical effort), as it has for centuries. In general, these risks are predictable and well understood, and force protection (while heavily reduced over the years) remains effective. In contrast, unpredictable demand will normally be driven by enemy action. The general threat of attack is predictable, but the timings and impact of attacks will be highly variable. Intelligent demand planning will enable more routine rather than emergent resupply, but as the enemy always has a say, the system will have to be ready for large and unexpected spikes. NATO modelling suggests high-tempo combat operations might reasonably result in 600 to 1,000 casualties per day, which anecdotally is close to the Ukrainian experience. In such MCI, the 50% or more triaged to the lowest urgency (“walking wounded”) have a survival rate of over 97%, even if care is delayed. Given that small, mobile surgical teams are extremely limited in their capacity, patients who do not need DCR cannot go to them, or they will be overwhelmed almost immediately. Three other treatment and evacuation pathways are therefore needed in parallel to DCR: treatment of minor injuries, returning the soldier to the fight; non-time-critical injuries that exceed the capability of Role 1 and so must move to high-capacity hospitals in the rear; and providing a comfortable, dignified death for those who will succumb regardless of treatment, without consuming resuscitation capacity that others need.

To manage four treatment pathways, Role 1 must be empowered to triage patients accurately, putting patients into the correct pipeline as early as possible. While triage is easy in concept, it is very challenging in reality. The systems taught in NATO are designed for the lowest levels of medical provider. They are simple, but that constrains their accuracy. Because medical resources were abundant in recent conflicts, triage was optimised to be sensitive – trying not to miss someone who needs DCR. Sensitivity is bought at the cost of specificity; the ability to protect resources by not allocating them to people who do not need them. Current systems are around 60% sensitive and 70% specific; in a 100-patient incident with “classical” casualty distributions (where 10 need DCR, 20 can be delayed and 70 are walking wounded) these tools would send 12 patients to the Role 2. Unfortunately, six of those would be “over-triaged”, not needing DCR, but displacing six others who did.

Over-triage can be mitigated by forward deployment of enhanced pre-hospital care. Existing force structures allow for two such teams in every medical regiment, led by an emergency medicine (EM) doctor. Thus far their role has been poorly articulated and rarely exercised. EM doctors have vast trauma experience and are highly capable of selecting out the patients who need DCR. Typically, they operate around 90% sensitivity and 85% specificity; in the above scenario they would also have sent 12 patients to DCR, but nine of these would have needed it. With enhanced capabilities such as ultrasound they may well be even more accurate. This layer of precision triage must be applied as soon after injury as possible, which will require real-time sharing of video and physiological measurements. This will obviate the need for casualties to be physically concentrated at the Role 1 for triage to take place. Forward EM can also start DCR at Role 1 for those who need it (assuming the Role 2 is not able to access them directly, faster), and will increase the capacity of Role 1. Casualties who exceed the capabilities of a reinforced Role 1 but do not need DCR typically require only limited medical input in the forward areas. They need to move to the rear as soon as it is safe. In many cases this might be facilitated by remote advice and monitoring from the enhanced Role 1.

The capacity of Role 1 to return soldiers to the fight must also be increased. At the moment, even relatively minor wounds (for example a 30 cm laceration) would normally move back to an Role 2/3 for management. Advances in pain relief; the ability to cleanse large and complex wounds; and the advent of smart dressings and splints, which could reduce pain, encourage healing and even warn of developing infection, may play pivotal roles in the rapid return to duty. Unfortunately, these areas are not privileged in terms of research funding. There should also be a focus on the “lowest capable provider” concept, artificially increasing the available workforce by protocolising treatments and innovating delivery mechanisms that make treatments safer and easier to administer, making them accessible to lower-trained personnel.

Palliation is a normal part of hospital medical care, but to be effective in war it needs to be firmly established at Role 1. It must be supported by effective training and development of protocols and equipment that allow patients to die in comfort and dignity, even in adverse and austere conditions.

Digitising Medical C2

The changes proposed above depend on data and effective C2. Mobile Role 2 and highly interconnected Role 1 telemedicine will come at huge cost in terms of bandwidth and assured communications. This will only get worse when commanders harvest the real-time information benefits of wearable devices (such as smart watches). If these become a normal part of the C2 architecture, it is inevitable that medics will take advantage of the ability to monitor the physiological state of the force. Closely linked to the problem of exponentially increasing information is the requirement for the medical C2 system to degrade gracefully in the face of electronic warfare. The system must assume that at times it will not be able to pass information freely, and so effective backup systems will be necessary. These challenges must not be taken on by Defence Medical Services alone, but rather must be rolled up into the similar and far larger problem faced by logistics as a whole. The capabilities and TTPs outlined above should improve the provision of medical support to deployed forces under modern battlefield conditions.

IV. Maintenance, Recovery and Repair

To use vehicles and equipment in combat is to have them damaged. Furthermore, high pressure, heavy weights and sudden travel on uneven surfaces put stress through vehicles and systems that guarantees failures. This is inevitable, irrespective of how well-designed a platform is, with or without the enemy. When the effect of fire comes into play, especially during offensive manoeuvre, it is evident that vehicles will be damaged in large numbers. Being able to recover and repair these damaged vehicles is the difference between the force being able to sustain its operations and degrading rapidly, losing mobility and combat power. Decisive damage to enemy formations is often achieved when maintenance areas are overrun. This chapter, therefore, explores how maintenance and repair can be improved.

Digital Twins and Predictive Maintenance

There are different approaches to maintaining complex systems around the world. The Soviet model was to track how long a system had been used and replace components at specified intervals. The assumption was that within a given period, some components would have become compromised, but the probability that enough components were damaged to impair the functioning of the device was acceptably low. This allowed for a systematic push logistics system for sustaining complex equipment like helicopters and electronic warfare platforms. NATO’s approach has largely been to continually check systems and repair them based on the identification of faults. This approach is maintenance intensive but allows for the fielding of more precise systems as the tolerances for a system where a proportion of parts are expected to fail are necessarily greater. The NATO system also requires spares to be called forward responsively when faults are discovered.

The concept of a digital twin has been pursued for some time. A digital twin is a digital representation of a system that accurately reflects how it is operating. The concept is becoming increasingly viable for two reasons. First, as platforms increasingly depend on software for their operation, the data they collect during operation on their own functioning is built in. It is not adding complex functionality, but exploiting what is already enabling the system to function. Second, as design has become digitised, files are also created against which the functioning of the system can be compared, so that digital twins can be calibrated at the point of manufacture. Comparison of the data received and the ideal performance characteristics can not only identify what exactly has broken but, as stress begins to move across a system to compensate for the irregular functioning of a component, detect that components are going to fail in the future.

The increased efficiency of predictive maintenance based on accurate mission data is best illustrated with helicopters. Using digital twins, Sikorsky has had the approved fatigue life of critical components in its helicopters extended by the Federal Aviation Authority by up to 75%, owing to the accumulation of precise data on fatigue over time compared with the assessed probable fatigue rate based on mathematical projections during the initial testing of the airframes. Using such models, it becomes possible to not only preserve functioning components for longer and reduce the time and tooling required in vulnerable positions to diagnose faults, but also to anticipate what may break, and thereby push forward and cache relevant spare parts before they must be changed. Digital twins therefore offer the opportunity to both reduce the forward logistics required by maintainers and to limit the footprint of those areas where vehicles are maintained.

Digital twins require that maintainers can plug into the system and download its mission data for transmission to update the twin at periodic intervals. One problem is that this reduces the viability of modifying vehicles in ways that cannot be represented in the twin. If additional armour or armaments, for example, significantly alter the pattern of vibration or weight distribution, there is a risk that faults will appear when the system is operating normally. Furthermore, basic mechanical systems that lack internal monitoring will not be able to generate the data to support digital twins. For this, and a range of other reasons, digital twins will likely be prioritised for those systems that are highly software enabled, such as air defences, and for complex systems such as helicopters. Autonomous vehicles will also be prime candidates to follow this process. Many platforms – where the aim is to reduce their unit cost and to ruggedise their performance – will not have a digital twin nor the sensors to self-monitor. It is therefore important that while this capability is seized where it adds value, it is not pursued by militaries in a manner that drives spiralling complexity and cost.

Managing an effective digital twin requires a different approach to intellectual property (IP) in contracting. During war, the adaptation of platforms must happen rapidly in response both to threat and to industrial pressures and supply chain disruption. If this adaptation cannot be paired with the digital twin, the system of predictive maintenance breaks down. However, if a company owns the digital twin, it essentially has a monopoly and a great deal of leverage in any adaptations to the platform. Militaries may argue that as they are buying the physical product they should also receive and own the digital product. The problem is that the digital product also necessarily contains IP that companies will wish to retain. The need to avoid being locked in to a single vendor must, therefore, be balanced against offering protection to companies’ IP.

Additive Manufacture and Modularity

With digital twins only relevant for a proportion of military systems, simpler mechanical systems and components can be repaired and maintained by other means, while similarly reducing the signature of facilities and the pattern of life caused by a constant flow of forward supply. The two most relevant methods are additive manufacturing and modular platform design.

The ability to hold large containerised 3D printers forwards means that mechanical parts can, as long as digitised drawings are available, be printed in response to need. Thus, if a vehicle suffers damage or a component fails, this can be reported and printed at the point of repair, with no need to hold large stocks of spares, locate them and transport them to the front. This reduces not only the movement of materiel but also the number of pieces of information that must be transmitted within the support system. There are issues with the longevity of 3D printed parts, and a risk that different heat treatment may displace stress to another part of a system, cascading damage. Advances in 3D printing will improve the fidelity of the parts, and often the longevity issue surpasses the anticipated life of the vehicle in combat, even if this is a sub-optimal approach for a fleet being maintained in peacetime. 3D printing does require raw materials to work. Raw materials can, however, be moved forwards more efficiently than finished parts. They generally pack more efficiently, and because a body of raw material can be turned into a wide range of parts, there is less wastage through the movement and stockpiling of parts that end up not being needed.

Many vehicles today contain complex systems that are not likely to be 3D printed forwards. Although additive manufacture is being used to print circuitry into the body of systems, for example, this requires highly sophisticated machine tooling that would not be economical to push forwards. Thus, while mechanical components can be printed and replaced on systems, electronic subsystems likely cannot. As the sophistication of these components increases, the skills and tools required to repair them also increase. Rapidly, the maintenance system begins to suffer from workforce constraints. The efficiency of the maintenance system can, however, be greatly bolstered through modular design. For example, vehicles are increasingly carrying complex sensors, from electro-optical balls to radar. These can and will be damaged if the vehicle comes under fire. They are very precise components and the tolerances involved mean that these sensors are unlikely to be able to be printed. The vehicle is also likely to be uncompetitive without its sensors. However, if the vehicle has a hard-point interface for the sensor, with contact surfaces that transfer power and extract data from a sensor, the maintainer can simply remove the entire damaged sensor, replace it with a new sensor and send the damaged sensor rearwards for it to be repaired in a location where appropriate equipment and trained personnel can be safely based. Unlike medical support, time for these repairs is non-critical. Modularity also enables the change of the sensor payload over time, noting that this may require updates to the mission data files on the vehicle to be able to ingest and display different kinds of sensor data.

The virtue of modular components in terms of the survivability of repair and maintenance is that they significantly reduce the time window during which maintainers are concentrated with the damaged vehicle. Rather than working on the platform, it becomes possible to simply approach it, remove the damaged modular part, replace it and withdraw with the damaged part. The standardisation of components, and in particular the hard-point interfaces, across a force can further facilitate this process, as it reduces the range of parts that must be held by the logistics system.

Deception as Force Protection

Despite the reduced signature and increased tempo of repairs achievable through precise systems monitoring, predictive maintenance, additive manufacturing and modular design, many vehicles will need to receive attention for a protracted period and may also require equipment with a large footprint. Changing the engine on a large armoured vehicle, for example, likely requires a crane, and even once a power pack is replaced, it often takes time to confirm that wiring and other sub-systems are interfacing with the system properly. Cranes have a large signature. Many of the systems used by maintainers – additive manufacturing, for example – also rely on power, so there must be an electromagnetic spectrum signature.

If it is accepted that repair systems are critical for maintaining tempo, then having repair sites in the indirect fire zone is unavoidable. One of the best means of protecting these facilities is through deception, rather than concealment. One of the advantages that repair workshops have in this context is that they have some of the best decoys possible: actual vehicles that have either been battle damaged or cannibalised and are therefore now disposable. The difference between a damaged or destroyed vehicle and one that is damaged and awaiting repair is not analytically easy to determine. It is also possible for functional vehicles to conceal themselves as damaged. Since maintainers have the tools for moving vehicles, they can hide in the noise of battle damage.

Even with these measures, however, there is a growing tendency for militaries to strike damaged vehicles to prevent their recovery. In many instances, vehicles can be more cheaply immobilised or damaged than destroyed, but once immobilised they can be economically destroyed when the battle allows. Again, deception is a key technique for preserving damaged vehicles from follow-up strikes. For example, the burning of tyres, or similar material, next to a damaged vehicle will product black smoke, which is almost always perceived as an indicator that the vehicle is on fire and will therefore suffer warping and other permanent damage from heat that will render it non-recoverable. This, and similar techniques like reporting the vehicle as destroyed over communications systems, can allow for damaged vehicles to remain in place for later recovery.

Even with these techniques, recovery and repair workshops will likely be pushed back. It will also therefore be essential to find protection from overhead observation for key equipment such as cranes. The use of industrial buildings, for example, is ideal because it provides overhead cover, as well as being mainly empty space. Battle damage assessment through corrugated iron roofs, for example, is difficult. Energy provision, meanwhile, can partly be handled through burying generators or drawing from civilian infrastructure in depth. The problem with this approach, like field hospitals established in hardened infrastructure, is that it is not dynamically available for different axes. However, unlike casualties, vehicles do not deteriorate rapidly over time once damaged, so the extended timeline to reach maintenance is not a mission critical constraint.

Conclusion

This paper has assessed the challenges presented to tactical sustainment operations during high-intensity warfare. The paper posits that the capacity to find and strike throughout operational depth makes sustainment functions increasingly vulnerable. Past procedures, from centralising sustainment hubs for efficiency to consistent handover points between echelons, and the combat arms setting the demand for sustainment functions, all exacerbate the threat and thus the sustainability of the force. To mitigate these challenges, this paper has argued that clusters of technologies are allowing the expanded application of well-established principles, including dispersion, deception and convoys.

The proposed adaptations to the sustainment of the force may make the force more resilient, but that does not mean that the planning assumptions with which combat arms plan and execute operations are unaffected. The volume of materiel that can be accumulated from dispersed caches, the duration of the window of opportunities to push or pull materiel along contested GLOCs, and the scale of operations at which genuine ambiguity is achieved all necessarily have significant implications for how the combat arms approach the expenditure and commitment of their units. Attempting to reach exact conclusions on these questions in this paper would be premature. It would require extensive wargaming and experimentation to produce a robust answer. However, several hypotheses as to the impact of contested logistics on combat arms activities can be suggested for further enquiry.

One critical question is the impact of the system described upon the tempo of operations. Mobile medical capability should enable medical provision to keep pace with advancing forces. By contrast, the ability to achieve ambiguity of cargo and to disperse reduces dramatically as caches must follow an advancing force. It follows that even using these techniques, a force has a limit of advance before its logistics can be targeted and its momentum severed. The critical question, therefore, is how far combat arms assess that they can punch, and how wide a salient must be before ambiguity and dispersion of support functions can be maintained.

Another critical question that arises for combat arms is the judgement of how much equipment can in fact be recovered. Once equipment is pulled back behind the FLOT, the techniques described in this paper may be able to obscure the repair process sufficiently to bring vehicles back into the fight. However, if recovering damaged vehicles proves non-viable, given the ability to cheaply and precisely deliver follow-up strikes, it may be that the proportion of equipment that is destroyed rather than damaged increases. If this is the case it may have profound implications for how vehicles are designed, for if it is not anticipated that they will be recovered and repaired, there will be a drive to minimise the number of specialist systems mounted on them.

There is also the question of the tail’s tail. A Role 2 hospital that must constantly traverse rough terrain is going to have breakdowns and may need mobility support to cross certain obstacles. A logistics system premised on dispersing caches off road needs a high level of mobility, but will wear out vehicles. Dispersed forces also need greater organic firepower for force protection. There will be a point at which the logistics system is consuming too much materiel and is limiting the efficiency of the force. Finding the balance is critically important.

The combination of understanding how many logistics vehicles can be efficiently sustained and how many caches can be pushed into an area before the logistics system loses its protection gives an indication as to how much materiel can be held within a given area. This in turn determines the size of combat arms that can be supported for a given front. This is a vital equation, because it sets the force density that the combat arms must be optimised to deal with, and thus the levels of mutual support, lethality and ammunition consumption that the force can sustain. Getting this equation wrong risks having the force overmatched along the front.

The point of these concluding observations is that far too often force development starts with the combat arms and then allocates sustainment resources based on their anticipated supply requirements. There is still merit to this process, but it is also important – now that sustainment functions are themselves directly threatened – to work in the other direction. Without calculating what size of forces can be sustained, over what distances and at what tempo, the risk is that armies try to build combined arms formations that lack stamina in the fight. Sustainment may be a means to an end rather than an end in itself, but if neglected, it will still lose a force a war.

Jack Watling is Senior Research Fellow for Land Warfare at the Royal United Services Institute (RUSI). Jack works closely with the British military on the development of concepts of operation, assessments of the future operating environment, and conducts operational analysis of contemporary conflicts.

Si Horne, Colenel, is the Chief of the General Staff’s Visiting Fellow at RUSI. An Army Emergency Medicine doctor, he has supported operations in Northern Ireland, Iraq, Afghanistan, Sierra Leone and South Sudan as well as serving as the Emergency Medicine lead for the Army.