This week, the Russian invasion of Ukraine turns four months old. While the Western world largely expected a rapid Ukrainian military defeat by Russian forces, the Ukrainian armed forces and their people halted the initial thrust of the invasion, and have since regained some of their lost territory and continue to defend their nation. The war is far from over. At this point, no one can describe with certainty the eventual outcome. That said, there is already much we can learn from this war. For the US joint force, and the Army in particular, that should include identifying major lessons regarding the conduct of large-scale combat operations on the modern battlefield. These lessons and their implications should then inform both near-term readiness—in the form of leader development, training, doctrine, force deployments and preparedness—and future force design across the DOTMLPF spectrum (doctrine, organization, training, materiel, leadership and education, personnel, and facilities).

We must always recognize that every war is unique and that none perfectly predicts the next. Certainly, our way forward must be shaped not just by the current conflict in Ukraine, but also by Gaza in 2021, Nagorno-Karabakh in 2020, Crimea and eastern Ukraine in 2014, Georgia in 2008, Lebanon in 2006, and of course the US and coalition counterinsurgency and counterterrorism operations of the first two decades of this century. Even still, there are three major implications from the war’s initial months that can and must directly inform the US Army. The first of those is the necessity for effective conduct of large-scale combat operations (LSCO) over operational distances and extended duration in time. The second is the necessity to be able to operate effectively and preserve combat power during the noncontiguous and nonlinear operations that characterize modern large-scale combat. The third major implication is the necessity to operate effectively against, partner with, and employ hybrid forces—that is, combinations of special operations forces, conventional forces, paramilitary and irregular forces, and others. Recognizing there are dozens of other lessons that have emerged or are emerging, these three major implications are especially relevant and should serve as catalysts for improving US force design, capabilities, operations, and preparedness.

Large-Scale Operations over Distance

The last time the United States Army conducted LSCO over operational distances and for an extended time was during the initial invasion of Iraq in 2003. In that invasion, the US Army employed one corps consisting of three divisions plus a few separate brigades. The Army elements operated alongside a Marine expeditionary force (MEF) consisting of one division plus separate elements, for which the US Army provided significant logistical support to enable the MEF to move from Kuwait to Baghdad. That invasion of Iraq was roughly the size of the current Russian invasion of Ukraine in terms of forces and distances.

As the world has witnessed, the Russian armed forces have had significant challenges in executing LSCO over distance since their invasion. After initial rapid thrusts, their offensive ground to a halt. In part, this was due to the inability to mass combat power at the necessary points to be able to break the Ukrainian defense. However, this is also due to an inability to sustain their forces over time and space. And, they have demonstrated an inability to secure their lines of communications, logistical support elements, and command posts against the threats in their rear area.

The obvious question for the US Army is whether we could do any better. At first glance, the Army’s experience suggests that we can—during the march north in Iraq in 2003, V Corps and US Army Central were able to maintain sufficient momentum to accomplish the initial campaign objectives. However, a review of the Army’s logistical system, as detailed in the book On Point: The United States Army in Operations Iraqi Freedom, suggests that system was strained and failed in several areas. Chief among the failures was the inability to move repair parts where needed to fix the wide range of weapons and other systems employed during a campaign. Another challenge was the ability to provide fuel to the advancing US forces. Again, as detailed in On Point, extraordinary measures were taken to ensure that armored vehicles, notoriously gas guzzlers, were able to receive sufficient fuel to maintain the offensive.

Another area that calls into question the US Army’s ability to conduct LSCO at distance and over time is training. Training at the brigade level and below conducted at combat training centers (CTCs) is, in terms of the scale of the operations in Ukraine, relatively small. And, the training is conducted for a mere two weeks, punctuated by so-called “battle periods,” in between which are administrative halts when units are able to rest, refit, and execute the full range of logistical support operations. Moreover, because of the small size of these training centers, the logistics system is never truly stretched, nor is it forced to operate at maximum performance over long distances, for extended durations of time. For example, the National Training Center, the US Army’s largest CTC, is roughly sixty kilometers long. In contrast, the distance from the Russian border to Kyiv along the Sumy access the Russians initially employed is approximately four hundred kilometers, requiring logistics support almost seven times farther than training at the National Training Center. Finally, while there are some operations at each CTC against the soft underbelly of the units—that is, their logistics, their command posts, and their service support units—there is nothing comparable to the scope and scale of the actions to which the Russian armed forces have been exposed by the relentless and widespread attacks of the Ukrainian army, the Territorial Defense Forces, and even individual civilians.

The US Army’s large-unit training—that is, corps and divisions—is conducted by the Mission Command Training Program during what are called Warfighter Exercises (WFXs). A WFX is ten days long—again, nowhere near the duration of a campaign or major operation such as the current war in Ukraine. WFXs are conducted in relatively small operational areas in terms of what could reasonably be expected of a division or corps in an actual campaign or war. And, most importantly, WFXs are conducted using simulations—digital, virtual wargames. That means that the current Army has no experience conducting live LSCO above the brigade level since the invasion of Iraq nineteen years ago. There is virtually no one in the United States Army below the ranks of colonel and command sergeant major who has ever experienced an operation larger than that of a brigade. Moreover, those colonels and command sergeants major were young officers and noncommissioned officers during the invasion of Iraq and saw only their small slices of the operation, probably at company level or below. The US Army simply has insufficient experience in LSCO over time and distance to be able to expect to perform considerably better than the Russians have in Ukraine. And, as suggested above, current training approaches produce no opportunity to gain that experience. The US Army must find a way to train, at a minimum, entire divisions, and preferably corps, physically in the field, at distance, and over time. That is the only way to gain the experience and solve the physical problems associated with LSCO. The DEFENDER 20 exercise was intended to conduct a large-scale training exercise with a full Army division in the field over time and distance on European terrain, but that exercise was canceled due to COVID. Since then no such exercise has been conducted. Now is the time to regenerate that effort and to make it a recurring event to regain the needed expertise in large-scale operations over distance and time.

Another challenge for LSCO over time and distance is that of intelligence. Such operations employ all-source intelligence (SIGINT, MASINT, HUMINT, OSINT, etc.), collected at all echelons from the scout platoons in a battalion to national-level assets. In the case where there are potentially multiple corps, consisting of multiple divisions, consisting of multiple brigades, the integration and synchronization of military intelligence collection becomes a huge and complex management and physics problem. That is not a challenge effectively trained in small bite-size chunks at a home station or with a single brigade at a CTC and then scaled up. Nor is it a challenge that can be trained effectively in a simulation. Simulations mask the scale and frictions associated with literally thousands of collectors and sensors being employed across vast areas for specific purposes and then aggregated together to create either common operational pictures for decision-making or specific target intelligence for a strike.

The military intelligence enterprise must be trained physically, at scale, in order to ensure effective intelligence support of large-scale operations at distance and over time. Ideally, this would be done in conjunction with divisions in the field. However, a low-cost alternative would be an “INTEX.” An INTEX would be a field exercise that includes only command posts and the physical employment of the full range of intelligence collectors and capabilities. For example, a corps at Fort Hood or Fort Bragg would have the capability to employ corps, division, and brigade collection capabilities in the field, physically integrating and synchronizing that collection across space and time against a notional OPFOR. At the same time, for deployed command posts, integration of military intelligence could be conducted within the command post to frame decisions for commanders and to produce targetable intelligence for a notional attack. This is similar in concept to a fire coordination exercise in which leaders and fires elements are in the field training, but there are no actual units subordinate to leaders. This type of intelligence training could actually improve the capability of the US Army to support large-scale combat operations over time and distance with effective military intelligence support.

Nonlinear, Noncontiguous Operations

Current US Army doctrine and training largely assumes that large-scale combat operations will be linear and contiguous in nature. What that means is there is an expectation of a forward line of troops (FLOT) in contact with an enemy who also has a forward line of troops, and that behind those FLOTs the area will be generally secure. In other words, the expectation is that the maneuver forces—infantry, armor, and scouts—will be in contact with the enemy, while other elements such as artillery, engineers, signal, air defense, logistics and administration will be relatively secure from direct-fire contact. Thus, there is an assumption of a broad-front attack and defense, with relatively secure rear areas similar to that experienced in World War II, Korea, and even Desert Storm.

What we have witnessed thus far in the Russian invasion of Ukraine has been nonlinear and noncontiguous. On the very first day of the war, the Russians invaded using very rapid and deep thrusts along roads aimed at key cities and objectives. At the same time, they used helicopter assaults to attempt to seize key locations, primarily airports. These rapid thrusts bypassed a large number of Ukrainian forces. As the war continued, so did these thrusts, as the Russian combat forces continued attempting to take the key towns and cities along the transportation network of eastern Ukraine. At the same time Russian support elements were not safe behind a contiguous Russian line of combat forces. Instead, they have been continuously exposed to attack from Ukrainian army forces, Territorial Defense Forces, and even ordinary armed civilians, to include emerging resistance in the southern regions. The Russian operational approach of these rapid thrusts on the first day of an operation is not unique to the current Russian invasion of Ukraine. In the 2014 seizure of Crimea, in the 2008 attack into Georgia, and as far back as the 1979 invasion of Afghanistan, the Russians have employed rapid deep thrusts in conjunction with airborne and helicopter assaults. Even in the initial peacekeeping movement into Kosovo in 1998, the Russians employed a rapid thrust to secure the airport in the Kosovar capital of Pristina. Thus, this approach is clearly a Russian preference and one that US Army and NATO might experience should conflict break out between NATO and the Russians.

Simultaneously, we must acknowledge that today’s military forces are not as large as those of World Wars I or II, or even Korea. Smaller military forces mean that in large operational areas linear, contiguous operations are almost impossible. The US Army experienced this in Iraq and Afghanistan, although under circumstances that were significantly less lethal and lower tempo than we are observing in Ukraine. Ukraine is an example of an operational area so large that major countries’ forces—those of Russia, the United States, or even the collective forces of NATO—cannot form a linear, contiguous defense or attack. In practical terms, with the exception of the eight-year-old line of contact with the separatist regions in Luhansk and Donetsk oblasts, the Ukrainian defending forces have been wildly separated from each other and forced to operate independently in small elements, particularly given the Russian ability to strike with artillery and airpower should the Ukrainian army mass for a counterattack. At the same time the Russian units are widely dispersed and support elements isolated and vulnerable to attack anywhere behind the front lines.

So, what are the implications for the US Army? First, the Army must recognize that future LSCO are likely to be nonlinear and noncontiguous. Second, we must adapt our concepts and our doctrine to better enable the US Army and the joint force to engage in noncontiguous and nonlinear operations. Third, Army training and leader development must prepare commanders, staffs, units, and soldiers to operate in a nonlinear and noncontiguous environment and succeed in their missions.

Current US Army doctrine does not adequately address this reality. The final draft of the new Field Manual 3-0, Operations provides little guidance for nonlinear or noncontiguous operations, either in terms of threat operations or in terms of our own. While noncontiguous areas are mentioned, how the Army operates differently from linear, contiguous areas is not addressed. Similarly, the doctrine for corps, divisions, and brigades makes little mention of such operations. For example, Army Techniques Publication 3-92, Corps Operations only addresses positioning the main command post differently if in a noncontiguous operation. It is only in the doctrine for reconnaissance operations, which are almost always nonlinear and noncontiguous, that any remotely substantive discussion of such operations appears. Moreover, the current concept for future operations, the Army’s 2018 TRADOC Pamphlet 525-3-1, The U.S. Army in Multi-Domain Operations 2028, assumes that enemy defenses will be linear in nature and makes almost no mention of nonlinear operations. It is for this reason that the operational approach is to penetrate defenses, then disintegrate and exploit such a penetration. In fact, the new reorganization of the United States Army division is called the penetration division. Penetration implies a linear defense on the part of the opponent, a clear signal that the Army doctrinally and conceptually still considers large-scale combat operations to be linear and contiguous in nature.

If the US Army is to adapt to the reality of nonlinear, noncontiguous operations, it requires a change in leader development. Leaders set the tone and establish the culture for any Army organization. Leaders determine how their organization will adapt to the changing character of warfare. Leaders ultimately are responsible for everything the Army does or fails to do. This levies a requirement on leaders to recognize the nature of nonlinear and noncontiguous operations and to take steps to transform the Army into one able to fight and succeed in such an environment. In order for that to occur we must develop leaders who understand, visualize, describe, and direct operations in such an environment. This cannot happen using a single class in the Command and General Staff College or an hour-long block of instruction in the Pre-Command Course. Instead, leaders must grow from their first courses as noncommissioned officers or officers to thrive in an environment of nonlinear and noncontiguous operations. That means that classroom instruction, practical exercises, and field training of leaders in professional military education and the noncommissioned officer professional development system must incorporate nonlinear and noncontiguous operations. Likewise, organizational and unit leader development programs must stress nonlinear and noncontiguous operations, whether in the form of staff rides, terrain walks, or professional discussion. Unit leader development and self-development must include reading about noncontiguous operations, so that leaders are educated in the theory, history, and practice of nonlinear and noncontiguous operations. And, perhaps most importantly, senior leaders must set the example by developing in their subordinates the understanding and application of Army operations in nonlinear and noncontiguous environments against an enemy who may very well adopt such tactics in order to defeat our campaigns.

Currently, the majority of Army training overwhelmingly emphasizes linear, contiguous operations. Army WFXs that train divisions and corps are based on scenarios that are linear in nature and assume contiguous frontage, with rear areas that are protected from significant combat. Training scenarios at the National Training Center in Fort Irwin, California and the Joint Multinational Readiness Center in Hohenfels, Germany are already adapting to what is occurring in Ukraine, but still include significant linear, contiguous operations. Traditionally, the Joint Readiness Training Center in Fort Polk, Louisiana stresses nonlinear operations. This is primarily because of the terrain and operational environment of the training area, and the fact that the forces that train there are primarily light infantry. More is needed. US Army training needs to adapt to present combinations of scenarios that are both linear and nonlinear, contiguous and noncontiguous to prepare the Army for a variety of future operational environments, missions, and threats.

Hybrid Operations

One of the characteristics of the Russian invasion of Ukraine has been the hybrid nature of operations—specifically, the mix of various types of forces involved. For example, the Russians have employed their Spetsnaz (special operations forces), conventional forces, separatists in the Donbas region, foreign fighters (in particular, Chechens), and mercenaries such as the Wagner Group. On the opposite side, in the defense of their country Ukrainians employed their own special operations forces, conventional forces, Territorial Defense Forces, civilians who volunteered to pick up weapons to defend their country, and foreign volunteers from other countries.

This mix of forces is significantly different from the largely symmetrical approach envisioned in US Army doctrine. FM 3-0, Operations and the doctrine for armies, corps, divisions, and brigades mention hybrid operations only in describing the threat, while combined arms battalion-level doctrine has only a single reference to hybrid threats. Moreover, we can expect that any partner with whom we operate will employ some combination of hybrid forces. For example, were NATO to actively support the Ukrainian forces and engage in combat operations alongside them (that is not being advocated for or against here) United States forces would have to integrate with these hybrid mashups employed by the forces currently operating inside Ukraine. From a policy, strategy, and operational perspective, the United States has declared that we will never fight alone as a nation, but always in conjunction with partners and allies. Thus, it is virtually impossible to conceive of a case in which our forces will not have to integrate with partner or allied hybrid forces, or oppose such hybrid forces. Accordingly, we must update our doctrine to account for hybrid forces, both enemy and friendly, in terms of what they are and how we operate with and against such forces. This must include doctrine covering the employment of US special operations forces and the Army’s security forces assistance brigades in order for these forces to enable full support of partners across the full spectrum of hybrid forces.

Another area where recognition of and approaches to hybrid forces is deficient is in training. The WFXs conducted for divisions and corps are based primarily on conventional force-on-force operations. While US Army SOF are usually included in the exercises on the friendly side and the enemy opposing forces (OPFOR) typically includes special purpose forces (similar to Russian Spetsnaz), the overwhelming majority of the activity, and hence the training of the commanders and staff, is in conventional force-on-force operations in the physical domain. There is virtually no training with hybrid forces of partners and allies, so that the staffs never have to think through how the US Army could work with those types of forces in partnership to accomplish operational objectives. These challenges could be corrected through restructuring the OPFOR in the WFX simulation, by adding hybrid partner forces to the friendly forces in the simulation, and through having role players from each of the various types of friendly hybrid forces to coordinate with staffs and commanders. Experience with hybrid operations in Operation Iraqi Freedom and Operation Enduring Freedom suggests that commanders and staffs consume a significant amount of time in coordination and relations with hybrid elements, time that is not available for planning, coordinating, and directing their own operations.

There is a similar challenge with the training at the CTCs for brigades and below. At each of them, there are some paramilitaries who operate in support of the OPFOR, but only by exception are hybrid forces operating with the rotational training unit. Thus, small units and leaders never get the opportunity to train in the way they are likely to operate in LSCO if partnered with another country’s forces or against virtually any enemy. This challenge can be corrected by deploying additional US Army infantry companies, or better yet allied and partner infantry, and having them serve as a variety of local guard, paramilitary, and civilian forces on both the friendly and OPFOR sides. The rotational training unit will learn to operate with and against hybrid mashups and the deployed infantry units will gain a better understanding of hybrid mashups by portraying them and fighting as those forces alongside or against the conventional units.

The implication of course is that a cultural change is required. The US Army can no longer afford the luxury of assuming symmetrical, conventional force-on-force operations. In everything we think, say, and do we must assume that all future operations will be hybrid in nature. Therefore, in our doctrine, our training, our organizations, and our leader development we must account for operating alongside mashups of forces and being opposed by other hybrid forces. We must recognize that such hybrid mashups will be different and unique to every operation and every threat. We must integrate these concepts into all of our professional military education, for our officers, warrant officers, and noncommissioned officers, at all echelons. That means in the Basic Officer Leader Course for lieutenants and the Basic Leader Course for junior noncommissioned officers, those first professional military educational opportunities, we must integrate hybrid forces, both in classroom instruction and field problems. And, that approach must continue in all of the developmental courses through the Army War College and the Sergeants Major Academy.

Similarly, we must adjust our organizational and material solutions to be able to rapidly integrate, partner with, and fight alongside friendly hybrid mashups in LSCO, as well as other operations. This means a focus on rapid interoperability, as each hybrid set will be unique. Absolutely critical will be training in how to communicate simply and effectively in order to coordinate planning and operations, and how to support each other logistically. Certainly in the current conflict, NATO, the United States, and the US Army have done very well in the provision of both lethal and nonlethal military support to the mashup of Ukrainian forces in ways that have enabled them to rapidly and effectively generate and employ lethal force. This has been done, as much as possible, by providing them equipment with which they are already familiar, but when needed by providing them equipment that is easy to learn and simple to operate. We have to be prepared to do the same in any future conflict.

The exploration of these three lessons from the war in Ukraine should serve as a catalyst for important, ongoing discourse. What must we learn from the Russian invasion of Ukraine—not just about the Russians as a threat, but also about ourselves—in order to best prepare for future conflict? Thinking through the implications of LSCO over large distances and extended time, noncontiguous and nonlinear operations, and operating with and against hybrid mashups of forces can reinforce and perhaps lead to adjustment of US Army modernization, force development, and preparedness. On a more practical level such discourse should be conducted in the halls of professional military education institutions, in the conference rooms of Army units, and on the ranges and training areas where we learn and practice our profession. And, hopefully the discourse will continue to include other relevant implications as we better understand the evolving character of warfare.

James K. Greer is a retired US Army colonel and former armor officer. He is currently an associate professor at the US Army School of Advanced Military Studies at Fort Leavenworth, Kansas. He holds a doctorate in education with a focus on military leader development.

The views expressed are those of the author and do not reflect the official position of the United States Military Academy, Department of the Army, or Department of Defense.

Image: A US soldier watches Ukrainian artillerymen fire the M109 self-propelled howitzer at Grafenwoehr Training Area, Germany, May 12, 2022. (credit: Sgt. Spencer Rhodes, US Army)