When Ukraine’s military launched a campaign in May to retake territory seized by Russian forces after their February invasion, Ukrainian MiG-29s were overhead, flying low and supporting the ground forces’ attacks. Around the same time, Ukraine’s Ministry of Defense announced the shootdown of a Russian Su-35 by a Ukrainian aircraft. In the four months since the war began, Russia has lost a staggering 171 total aircraft, including thirty-four fixed-wing combat aircraft, many of them to Russian ground-based air defense systems.
Among the many ways in which Ukraine’s military capabilities in the war have surprised analysts is the degree to which Ukrainian forces have continued to contest the air domain. From air-to-air combat to close air support for ground forces to effective air defenses, Ukraine has outperformed virtually all expectations. How it has done so is the source of important lessons for US airpower. In particular, examining the resilience of the Ukrainian air force, specifically within the context of the US Air Force’s emerging agile combat employment (ACE) concept, reveals ways to maximize that concept’s potential against a capable adversary on a highly lethal, hyperactive battlefield.
To be sure, many analysts have rightly pointed to Russian ineptitude across a variety of functions at all levels of war as a leading factor in both sides’ performances so far, and it would be fair to suggest that any lessons learned must be tempered with the realization that Russian capabilities were largely overestimated in the lead-up to war. There are aspects of Ukraine’s success, however, that deserve closer scrutiny and have far-reaching implications for the US military in other theaters. The war in the air is one of these.
The survival of the Ukrainian air force was not purely the result of a single-service endeavor but a function of a joint effort that would not have been achievable without ground-based air defense, distributed basing supported by ground troops, and a willingness to adopt the philosophy of mission command—which has important implications for the US joint force. Moreover, the war’s conduct offers a jumping-off point to explore opportunities ACE creates when employed by an even more technologically advanced air component like the US Air Force. Finally, the war provides a real-world conflict scenario that can act as a framework for a discussion on the ways the US Army can enable ACE as part of joint all-domain operations. Ultimately, understanding and acting on these lessons from Ukraine may be the key to mitigating any military threat—whether posed by Russia in Europe or China in the Indo-Pacific—and ensuring air component and, by extension, joint force survival should deterrence fail.
Agile Combat Employment in Application
In December 2021, the US Air Force’s Lemay Center released Air Force Doctrine Note 1-21, Agile Combat Employment. This document is an expression of the way the US Air Force intends to mitigate a peer adversary’s technological advancements in intelligence, surveillance, and reconnaissance and all-domain long-range fires, a reduced global force footprint, and the increased risk to air bases with aircraft no longer able to operate from relative sanctuary. The concept is defined as “a proactive and reactive operational scheme of maneuver executed within threat timelines to increase survivability while generating combat power throughout the integrated deterrence continuum.” Applied as intended, it “complicates the enemy’s targeting process, creates political and operational dilemmas for the enemy, and creates flexibility for friendly forces.” It is a natural doctrinal reaction to a changing operational environment and the evolving character of war.
While tragic in most respects, the war in Ukraine provides the US Air Force with a rare opportunity to observe a near-peer threat in action and use the lessons learned to adapt the ACE concept. The Ukrainians—faced with extreme asymmetric challenges, difficult environmental conditions, and an obligation to support Ukrainian ground forces—have, by necessity, adopted many of ACE’s tenets into their concept of operations. Given the historic close cooperation between the US Air Force and Ukraine, the Ukrainian air force’s employment of ACE principles is unsurprising. It could be argued that ACE has both informed and been informed by the Ukrainian experience since 2014. While much of the Ukrainian air force’s activities since the invasion remain a closely guarded secret, what we do know from open sources is extremely illuminating.
In the days leading up to the February 24 invasion, Ukrainian aircraft dispersed from major operating bases and into alternate forward operating sites and contingency locations away from cities and toward the west. These alternate sites included short airstrips and highways. Russian forces’ initial air attacks were only moderately successful, owing to a lack of precision-guided munitions, poor air-ground integration, and a reluctance to leverage the full weight of their capabilities in the early days of the fighting. This failure allowed additional Ukrainian aircraft to escape in the first seventy-two hours. The Ukrainian air force, outclassed technologically, very quickly adapted its tactics, techniques, and procedures to pursue an aggressive defensive counterair campaign. Through detailed joint integration with Ukrainian ground-based air defense, along with residual and nonstandard ground-based sensors, which included a network of civilian spotters to support command and control, the Ukrainian military established a remarkably effective and resilient integrated air defense system.
Virtually overnight, the Ukrainian air force changed its approach to air operations to meet the situation. Using its aircraft as bait to lure unsuspecting Russians into surface-to-air missile engagement zones, the Ukrainian air force discouraged undertrained Russian pilots from entering Ukrainian-controlled airspace. Operating under the cover of their ground-based air defense, Ukrainian air crews surged sortie generation far beyond expectation and continued to provide close air support to ground forces as the defense of key political centers intensified. The Ukrainian air force further complicated Russian targeting by generally remaining at low altitude, below where Russian ground-based radars could detect the aircraft, and returning after missions to different airfields from where they started, keeping Russian intelligence guessing as to Ukrainian air force strength and bed-down locations.
On March 18, Russian frustration over the inability to penetrate Ukrainian-controlled airspace and growing international support for Ukraine boiled over and resulted in the first combat usage of a Kinzhal hypersonic weapon. This strike was delivered against a munitions warehouse in Delyatin and was notable for two reasons. First, it demonstrated the adversary’s reliance on strategic, expensive, low-density weapons, to achieve tactical effects against an operationally insignificant asset in the face of a difficult targeting environment. Second, it reaffirmed the continued and enhanced vulnerability of stationary targets to modern weapons. Despite this, the skies over Ukraine have remained, in the words of Pentagon spokesperson John Kirby, “contested”—a condition that can pretty much describe the state of the entire invasion at this point. The Ukrainian air force’s resilience in the defense bought time for the international community to assist Ukraine in generating combat power in the skies. During the week of April 19, Ukraine received both repair parts and complete airframes to bolster its beleaguered MiG-29 fleet. As a result, months into a conflict that many expected would last a week, the Ukrainian air force’s disciplined approach and adherence to the operational tenets of agile combat employment have ensured that it is not only still combat effective, but able to deliver airpower in support of Ukraine’s defense.
Two features of Ukraine’s performance in the war, particularly in the air domain, are important to point out here. First, the Ukrainians credit security force assistance and training with US and NATO partners as being the decisive factor in creating a professional, flexible, and disciplined force capable of the ingenuity and resilience required make this transition under stress. By adopting and implementing the mission command philosophy of command and control, which pursues the conduct of military operations through decentralized execution based on mission-type orders, the Ukrainian military had the basis for improvisation that their Russian adversaries did not.
Second, outcomes have varied considerably based on the extent to which Ukrainian forces have been able to operate jointly. In areas around Kyiv and in the north, the effective close air support the Ukrainian army received, even when it was limited, was reciprocated by sustainment and base-defense support from ground forces. Where Russia was successful, most notably in the southeast around Mariupol, Ukrainian high- to medium-altitude air defense, specifically S-300s, were absent. In these areas, the Ukrainian air force had significantly reduced freedom of maneuver and the other services were forced to largely fight independently with a subsequent negative effect on the military’s ability to retain ground.
Lessons Identified: Practical Requirements for ACE
To explore the implications of the lessons drawn from the war in Ukraine for the US military, it is useful to consider a scenario with several defining characteristics—certain conditions that exist at the onset of hostilities. First, US forces would initially be at a numerical disadvantage and would be forced to project power into the joint operations area. Second, political considerations and a desire to de-escalate would prevent US forces from taking preemptive actions against enemy forces that would obviate their advantages. Third, there would be some unambiguous warning of an impending attack from which prudent decisions could be made to mitigate the effects of the enemy’s first strike. Lastly, there is a strategic requirement that compels the military to fight from a position of tactical disadvantage. This requirement could be due to a treaty, limited access to a particular resource, or a position that must be retained to be successful over the long term.
This is a scenario for which ACE is optimized. If the United States is challenged to achieve and maintain air superiority, ACE offers a means of employment until sufficient freedom of action is achieved through force generation and the cumulative effects of convergence. Once freedom of action is achieved, however, the Air Force should revert to more traditional and efficient forms of employment. The virtue of the classic centrally controlled, decentrally executed approach to command and control for air operations will remain dominant in a minimally contested environment and from a planning and logistics perspective enables both simplicity and economies of force.
As in Ukraine, prudent planning would suggest that prior to and during the initial phases of the operation, when the capabilities, intent, and effectiveness of the enemy are not fully understood, ACE should be maximized to prioritize survivability while maintaining effectiveness. The agile combat employment doctrine note identifies some of the requirements to effectively accomplish this and highlights that this protection effort should employ both active and passive air and missile defense measures, enhance the ability to withstand attacks against logistics, and utilize an optimized command-and-control structure built for purpose—all of which we have been observed in Ukraine.
Despite this, there would obviously be differences in implementation. US application of ACE would be more effective than Ukraine’s in some respects, but more challenged in others. Of note, the technological advantages that our aircraft rely on in the skies become liabilities on the ground, requiring significant support in advanced facilities and maintenance areas. Additionally, the relatively short ranges of modern fifth-generation aircraft increase the requirements for fuel, which will be difficult to supply when operating in a distributed environment. This refueling problem will be exacerbated by the inability of the Air Force’s large, slow, airborne aerial refueling assets to operate inside an enemy’s surface-to-air missile engagement zone. Ammunition management will also be problematic, as the United States will continue to rely on precision-guided munitions to reduce collateral damage and improve lethality. The scarcity and handling of these munitions also require special equipment and training. For these reasons and others, ACE is predicated on the Air Force training what the concept calls “multi-capable Airmen,” who are expected to accomplish “tasks outside of their core Air Force Specialty.” This reduces the amount of ground support personnel but increases the burden on those that remain. On the upside, even with limited assets available, the qualitative overmatch of US training, approach to command and control, and equipment will create greater opportunities to put adversaries in positions of disadvantage and secure the initiative. This will enable earlier and more effective offensive operations following the adversary’s initiation of conflict.
In reviewing the requirements for ACE, it becomes evident that the capabilities needed for execution at scale—ground-based air defense, robust ground sustainment, and resilient and ubiquitous command and control—do not wholly reside in the US Air Force or exist in sufficient quantity to maximize the concept’s utility. Much like the Ukrainian military’s experience, the US Air Force’s employment concept will require joint interdependence. The service will need to rely on key capabilities from the joint force, particularly the Army—including air and missile defense as well as common-use capabilities such as engineering support, logistics, and transportation—to facilitate the continuous employment of the Air Force. These requirements may deepen if air lines of communication become frustrated due to overflight and basing concerns as they did in the early days of the Ukrainian conflict. Additionally, the joint force should also retain and expand the ability of its air traffic service arms to establish expeditionary dual-use airfields, which expand the menu of command-and-control options for basing fixed-wing aircraft. ACE will also increase the conventional base-defense requirements necessary to protect aircraft from ground attack in the rear areas. In truth, while ACE is presented as an Air Force employment concept, it is actually a joint employment concept, with the air component as the supported commander. Presented from this perspective, it is easy to see why other components may not be eager to expend energy that redirects combat power and resources from their own operations, while seemingly not providing a significant and immediate return on investment as the joint force struggles for air superiority. This, however, is a shortsighted view.
Joint Incentives for Cooperation
When we think about new concepts such as ACE, simple ideas tend to quickly get muddled in jargon and buzzwords. In cases like these, it helps to use an analogy to put things in perspective. Boxing provides us with a great analogy for agile combat employment, just as it does for joint warfare in general. Successful fighters cannot be one-dimensional. They must maintain the ability to dodge, weave, slip a punch, and play defense to ensure that they are still conscious to attack. Part of that defense includes establishing the jab to set up the knockout punch. In ACE, support between the joint services has a similar effect, creating opportunities for exploitation. This is essentially what the concept is all about, working together as one body to survive and succeed.
If the land component can support the retention and generation of air combat power closer to the point of need, those assets can enable combined arms maneuver more effectively. In the Ukrainian example, air component survivability in the forward areas correlated to increased sortie generation as the air force operated distributed within relative proximity of forward troops. With ACE, an air force is more responsive to ground alerts and can operate at greater depth when conducting interdiction and strategic attack missions. Additionally, ACE can provide greater strength to the defense by integrating more closely with ground-based air defense and providing more on-station persistence within the battle area. Once conditions allow the joint force to transition to the offense, ACE ensures that an air force still exists to do so, as the Ukrainians observed to great effect during their April counterattacks that retook Kharkiv. When the ground component truly considers the return on investment of ACE, it essentially equates to leverage, accelerating gains exponentially upon seizing the initiative.
In an all-domain operational context, the main effort might shift between domains as opportunities and threats arise. The Army multi-domain operations concept describes “windows of superiority” that will open and must be exploited—regardless of domain. Therefore, just as a joint force commander would direct the air component to support the land component with close air support if it enabled the ground force’s survival or was critical to maneuver, regardless of whether close air support is the most efficient use of aircraft, that commander might just as likely order other components to support ACE. The question at that point is simple: How well have the joint services postured themselves to take on this role?
Common Ground in the Skies: Mutually Beneficial Support
Importantly, there are investments the Army and Air Force should consider to enable Army support to ACE in a high-intensity, large-scale combat operation against a peer adversary—opportunities for partnership that will enhance joint force effectiveness in such a scenario. Among them, although this list is by no means exhaustive, are low-cost cross-domain fires, more versatile command and control that can rapidly create alternatives for destroyed, degraded, and denied major operating bases, and most importantly, joint training with the critical components of the ACE enterprise.
Fires are central to Army modernization efforts—air and missile defense and long-range precision fires account for two of the service’s six modernization priorities. This is directly relevant to ACE, particularly the ways in which cross-domain fires can support the concept. As observed in Ukraine, the presence of robust ground-based air defense is critical to the survival of the air component and control of the skies. Unfortunately, continuing to field sophisticated systems is both cost prohibitive and subject to long production lead times that won’t meet the demands of an environment that rapidly consumes resources. As an example, PAC-3 interceptors, at three million dollars each, are superb weapons but are in extremely short supply relative to the threat. An alternative is necessary to conserve valuable PAC-3s and other low-density munitions for appropriate targets in order to prevent the gap in mid-range coverage that the Ukrainians experienced in Mariupol.
One possible solution is the introduction of directed-energy weapons that could be used with vastly reduced costs and logistics requirements compared to traditional missiles. Another, more versatile option may be to enhance the fire control systems on cannon artillery to allow them to become dual-role fire-support solutions for air defense. The Army, with Air Force assistance and sensors, demonstrated this was possible in September 2020 at White Sands Missile Range when an M109A7 using a hypervelocity projectile achieved virtual intercept speeds of Mach 5. This capability would allow Army 155-millimeter howitzers to rapidly and inexpensively provide both air defense and ground defense and attack coverage in support of ACE or frontline maneuver. From a sensor standpoint, increased usage of highly mobile multimodal radars, like the Q-53, operating in an air defense role, can also create a more robust kill chain and thicken the integrated air defense structure necessary to support forward basing. This novel approach to integrated air defense needs to advance beyond the realm of one-off experiments and into an operational setting. This will require rethinking, replanning, and retraining with respect to how we use Army sensors and systems to reinforce the existing integrated air defense system by phase, location, and requirement.
Next, the land component will need to examine how it preserves and expands its ability to support forward basing and command and control for its air assets, which will also enhance support of ACE. The ability to rapidly establish short-duration air traffic services (ATS) under austere conditions is critical to the ability of all aviation to survive and support large-scale combat operations in a dynamic environment. This understanding has historically driven Army ATS to be distributed down to the lowest tactical level in the form of ATS companies in combat aviation brigades. These ATS companies currently retain sufficient capabilities—trained personnel; the Air Traffic Navigation, Integration, and Coordination System (ATNAVICS); and other equipment—to establish air traffic control for both rotary-wing and fixed-wing assets on an expeditionary basis for missions of short duration and limited scope. Retaining this structure provides the Army a great deal of flexibility and the potential to support the joint force, at the tactical level, through joint all-domain operations and ACE. Outside of the Army, the Marine Corps also has air traffic control capabilities that rely on the same ATNAVICS equipment used by the Army, creating the opportunity for even greater flexibility on the joint battlefield. Ultimately, the difference between the services in this regard rests largely in capacity and scale, not necessarily on capability. Increasing interservice ATS support would just need to be trained to proficiency to instill confidence in the joint force. As both the Army and the Air Force are seeing heightened demand for increasingly limited, tactically distributed air traffic services, it would seem mutually beneficial to collaborate on efforts to fill joint ATS requirements both in terms of manning and equipping. This would build redundancy and resiliency into an otherwise fragile basing system.
Finally, and arguably more important than the material and doctrinal aspects discussed previously, are the improvements in joint training and education that must be made to enable the success of ACE against a peer adversary. This was the lesson that the Ukrainians themselves drew from their first encounter with the Russians in 2014. That period, during which the Ukrainian air force was ineffective in the contested areas over Crimea and the Donbas, drove a sense of urgency in the subsequent eight years to increase trust in joint interdependence and saw extensive training between Ukrainian ground-based air defense and the air force. This enhanced efficiency and effectiveness within the Ukrainian military in those early critical days of the current fight.
As the United States continues to evolve the ACE concept it must learn from the Ukrainian example and look toward joint training at the tactical level to address the challenges and opportunities highlighted by this approach. As one might expect, to date, most of the training conducted on this concept has been executed by its originator, the US Air Force, through experimental exercises like the Agile Flag series, with limited involvement from the other services. While these exercises train the Air Force to be more flexible and expeditionary, Agile Flag doesn’t reflect what the Air Force can and should expect from joint interdependence because it doesn’t yet include the Army or Navy in any meaningful way.
One of the most significant leaps forward, from an ACE joint training perspective, was last year’s Northern Strike exercise, an Army and Air National Guard event that saw the first ever highway landing by modern military aircraft on US soil. This exercise also highlighted the value of the newly established National All-Domain Warfighting Center in Grayling, Michigan whose connection with local Air National Guard installations provides a unique series of Army and Air Force joint training venues. While still not perfect, Northern Strike provides a great example of the type of events the joint force should be doing and the type of training areas they should be developing.
Unfortunately, in the active force, where culture and risk aversion tend to inhibit our ability to train with the other services, we have yet to take full advantage of venues like this or replicate these experiences at our training centers. If we expect the future fight to be all-domain, then we need to train as we fight. That means joint training, which in turn requires greater risk acceptance and increased collaboration within the active component. Specifically with respect to ACE, we must develop joint training packages that deploy to combat training centers and work on specific aspects of the concept as a joint team. For example, Air Force wings can partner with Army air defense artillery brigades and combat aviation brigades to work on pieces of the ACE concept and conduct event-based training that supports the familiarity and trust necessary to operate in the inherently risky environment of large-scale combat. This type of activity should be prioritized, promoted, and actively resourced by the most likely combatant commands who will rely on ACE, US Indo-Pacific Command and US European Command.
The End of Round One
As this war of attrition drags on into the summer, the effects of the Ukrainian airpower approach are making the Russian invaders pay for every inch of territory. As of the writing of this article, in the skies over Kherson and elsewhere, the air component has regenerated sufficient combat power to continue to support its ground forces effectively as they attempt to wrest the initiative from the Russians. This news, while heartening, should be taken with a measure of caution. Russia retains a large military and if its forces continue to press the conflict they may yet find a way to win a protracted war, especially if Russia fully mobilizes and institutes some significant reforms. History has shown that the Russians are a dogged and determined foe and are willing to sacrifice greatly to achieve victory. If the US military finds itself confronted by a similar enemy on the future battlefield, will that enemy perform with the same ineptitude that has dogged its operations in Ukraine? Unlikely.
To return to the boxing analogy, the Ukrainians’ tactics and employment techniques have thus far helped them to evade the Russian knockout blow, and are now allowing them to rise from the canvas like Rocky Balboa and go one more round. Learning from their experience is vital, not least because in the next fight the United States may find itself not as the salty, supportive corner man, providing sage advice and aid from outside the ring, but instead the man in the arena himself, facing a much larger, smarter, and more dangerous opponent. If we don’t collaborate as a joint force to learn from the Ukrainians, and make the material, doctrinal, and training modifications to perfect the ACE technique, we could find ourselves fighting for our lives with one arm tied behind our backs. The Chinese are already in the gym right now, learning from the mistakes of the Russians and getting stronger by the day. They will be better tomorrow. Will our own agile combat employment be ready?
Lieutenant Colonel Matthew Arrol is currently serving as the commandant of the US Army Joint Support Team at Hurlburt Field, Florida. A career field artillery officer, he is a contributing member of NATO’s Integrated Capabilities Group on Indirect Fire and a graduate of the Command and General Staff College. His civil schooling includes a bachelor’s degree in history and political science from Michigan State University and an MBA from Eastern Michigan University. His most recent operational assignment was as the deputy commanding officer of the 19th Battlefield Coordination Detachment.
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 credit: Master Sgt. Sean M. Worrell, US Air Force