Winning the Air Battle for Taiwan: Lessons from Ukraine’s Drone Operations
Military strategists will be studying the reasons behind Russia’s confounding failure to rapidly defeat Ukraine for years to come. But there is one point upon which they seem to have quickly reached agreement: low-cost, easy-to-use drone technologies are playing a pivotal role in repulsing Russia’s advances. Drones have transformed what were once “dumb” artillery rounds into precision weapons to attack Russian armor and personnel with devastating effect. Ukraine was first to adopt low-flying quadcopters as artillery spotters, but Russia quickly caught on after losing so many of its Soviet-era drones to Ukrainian air defenses early in the war. Commercial quadcopters made by DJI, a Chinese military company, have now become so ubiquitous on the battlefield that sometimes neither side is sure of their provenance. Russian leaders now hail DJI drones as a “symbol of modern warfare.”
The U.S. national security establishment is now looking to draw lessons from the creative employment of drones in 21st century interstate conflict. Careful analysis is essential as these lessons will inform U.S. Air Force, U.S. Navy and the U.S. Marine Corps efforts to develop next-generation combat drones to shore up deterrence in the Indo-Pacific. One candidate lesson highlighted in these pages and elsewhere suggests Ukraine’s survival to date hinges largely on its ability to defend itself by simply contesting airspace with air defenses and an arsenal of low-cost drones consisting largely of homemade and commercial varieties that fly below adversary inhabited aircraft and air defenses. Maximilian Bremer and Kelly Grieco coined the term “air denial” to describe the new approach to deterrence, and advocate for the U.S. Air Force to adopt it as a “core mission.”
But U.S. national security leaders should not assume an unproven air denial approach, centered on relatively inexpensive missiles and drones, can become a centerpiece of American deterrence strategy. The air denial concept might have value for a weaker defender like Taiwan, which can learn from Ukraine’s effective use of layered, low-cost defenses to reduce (though not eliminate) missile strikes on its sovereign territory. However, the U.S. military’s operational concepts and technologies – including its next-generation combat drones – must be tailor-made to solve the nation’s unique strategic and operational problems. Viewed through this lens, air denial is not a sensible approach for the U.S. Air Force, which is called on to deter, fight and win the nation’s wars. Ukraine is in a fight for survival that hinges on holding and clearing ground in close-in, pitched battles. But U.S. forces are called on to project power over great distances to defeat highly adaptable, technologically advanced adversaries like China. The Air Force may struggle to control airspace in a great power war, but it should not throw out 100 years of air superiority doctrine to simply settle for contesting it. The outcome of America’s next war won’t be decided by quadcopter dogfights, so the Air Force’s next-generation combat drones will need to look and operate very differently than what we have seen to date in Ukraine.
The Department of Defense and Air Force leaders should reject an air denial approach for U.S. forces in the Indo-Pacific. There is little reason to suggest that a force built for air denial, centered around low-cost, short-range drones and air defenses, can deter a Chinese invasion of Taiwan. What the Air Force requires is a mix of crewed and uncrewed capabilities that can reach inside the range of Chinese weapon systems to rapidly attrit their invasion forces. Drones play a central role, but the drones that will make a war-winning difference for U.S. forces are not the drones of Ukraine. Air Force drones will need more range, survivability, autonomy and sophisticated sensors and payloads to bring real coercive leverage to the table.
Deterrence by Denial and the Future of Drone Warfare
The types of drones the Air Force needs to defeat China in a great power conflict should be determined by an assessment of what the service will be asked to do. While this sounds obvious, today there is no clear consensus regarding the approach that U.S. military forces should take to defeat large-scale aggression by great powers. The 2018 and 2022 national defense strategies call on U.S. forces to deter large-scale aggression through a strategy of deterrence by denial, which involves building the forces, postures and capabilities to credibly convince adversaries that aggression is infeasible or unlikely to succeed. As RAND analyst David Ochmanek explains, denial is “self evidently” the most credible deterrence strategy for the Indo-Pacific because it confronts China with the prospect of failing to forcibly absorb Taiwan. Furthermore, it does so in a way that is more credible and less escalatory than threats to impose costs on the aggressor. But what would a denial campaign practically look like? This is still a subject of debate and yet it has huge implications for how the services organize, train, and equip their forces to deter and defeat aggression by the nation’s most capable adversaries.
Perhaps the clearest articulation of a denial strategy is Ochmanek’s concept of blunt and hold, variations of which have been espoused by some influential U.S. defense leaders. In general, blunt and hold sets a high bar for deterrence because it requires the U.S. military to field forces that can rapidly sink large numbers of China’s military vessels, submarines, and cargo ships, as well as any air mobility aircraft delivering invasion forces. The objective, of course, is to implement this strategy on the battlefield before the People’s Liberation Army (PLA) can secure a lodgment on Taiwan and present the United States with a fait accompli. In such a campaign, the Air Force would need to rapidly deliver striking power at scale – against potentially tens of thousands of Chinese military targets, and to do so with little advance warning. U.S. forces would be up against China’s long range missiles, which would make it difficult for the Air Force to gain and maintain air superiority. To contribute to a blunt and hold campaign, next-generation drones would need survivability, range, and the right sensors and payloads to operate inside China’s formidable network of missiles, radar, and electronic warfare systems so they can sense and detect invasion forces and kill targets of opportunity.
Air denial offers an alternative strategic approach with very different implications for force structure and drone concepts and technologies. Bremer and Grieco argue that blunt and hold is too complicated and costly because it requires projecting power into contested areas to stop a Chinese invasion by employing advanced, survivable technologies such as inhabited aircraft, submarines, and long-range low-observable munitions. Such a strategy is becoming increasingly unsustainable, they argue, as evidenced by the rising costs of advanced crewed warplanes. In his thoughtful piece on the need to examine alternatives to blunt-and-hold, Evan Montgomery notes that blunt and hold also requires the U.S. military to keep assets in a high state of readiness for both early warning and rapid response. Maintaining such a force-in-being is financially taxing and could ironically create opportunities for the adversary. China is practiced in wearing down opponents through peace time cost imposition, he notes. So, an obvious option for Beijing is to raise and lower tensions just enough that the financial and political costs of the U.S. maintaining a rapid attrition posture in the Indo-Pacific become prohibitive over time.
Bremer and Grieco see air denial is an attractive alternative because it would allow the United States and allies to flip the cost exchange ratio in favor of the U.S forces. By eliminating the need to field the force required to rapidly attrit adversary invasion forces, air denial lowers the bar to simply forward-deploying assets to deny adversaries freedom of movement over allies’ sovereign territory. Bremer and Grieco point to what they see as the success of air denial in Ukraine, where neither side has been able to gain air superiority. They argue that air defenses effectively deny sanctuary at high altitudes and commercial drones contest the airspace in the lower altitudes – what they refer to as the “air littoral.” However, it’s not clear that drones have actually contested airspace at lower altitudes; they don’t regularly shoot down Russian aircraft.
Applied to great power conflict, Bremer and Grieco do envision a meatier version of air denial, which involves creating an “aerial minefield” over U.S. allies’ sovereign airspace, where thousands of drones, low-flying missiles, loitering, munitions, anti-aircraft artillery, electronic warfare systems and shoulder-fired missiles work in concert to stave off incoming invasion forces. Deployed on Taiwan or NATO’s Eastern flank, they envision air denial as the backbone of a strategy to increase both the costs and uncertainty of Chinese and Russian efforts to rapidly seize territory. This approach, at least, places greater emphasis on killing invasion forces, which is exactly what deterrence by denial requires. That said, the argument still has serious weaknesses as applied to U.S. forces and operational problems, and there is no evidence to suggest it’s a valid blueprint for U.S. force planning.
Air Denial, Denied
Based on the experience of Ukraine, Bremer and Grieco recommend the Air Force dramatically change its force structure. In their view, the Air Force should move away from penetration and precision strikes with inhabited aircraft in favor of an air denial concept built around drone swarms and air defenses. But air denial has two fundamental flaws: it overestimates the deterrent impact of contesting airspace, and at the same time, underestimates the deterrent impact of air superiority and power projection. A force structure tailored to air denial would dramatically erode the coercive power of the U.S. Air Force, with serious consequences for U.S. strategic deterrence.
The principal problem with air denial as a deterrence strategy is there is no evidence it works. Bremer and Grieco argue it can preserve the status quo, but a quick look at any updated map of Ukraine shows that it has not deterred Russia from occupying territory. Equally important, Ukraine has not been able to prevent serious and ongoing damage to its national infrastructure and population. Ukraine continues to contest Russia’s annexation of four of its eastern provinces, while Russia continues to launch offensives against Ukraine. At best, air denial has kept Ukraine in the fight, although how much of that is due to Ukraine’s adroit employment of air denial, versus Russia’s own ineptitude in achieving air superiority, is debatable. Assuming it’s the former and not the latter, air denial might be a useful asymmetric approach that allows weaker allies like to Taiwan to at least ensure that, if an invasion starts, it will be long, bloody and difficult. But the evidence from the war in Ukraine suggests even a force well-positioned for air-denial can’t prevent an invasion entirely, and Russia’s persistence in Ukraine proves the point that once they invade, revanchist powers are likely to knuckle down for a win despite a weaker defender’s resistance.
Another weakness of air denial is that it ignores the central role of power projection in U.S. national security strategy. The Air Force anchors the U.S. military’s ability to project large-scale military power over intercontinental distances and conduct sustained operations – a capability essential to offset imbalances in military power in the Indo-Pacific and Europe. Power projection goes hand-in hand with air superiority because, without at least small, limited windows of air control, it’s not possible to reach into adversary airspace to rapidly attrit invasion forces. Air denial, in contrast, seems to minimize the need for power projection and air superiority in favor of contesting airspace in a defensive posture – what Bremer and Grieco call “defense-in-vertical depth.” Such a posture may cost less in the planning stages, but it also cedes sanctuary to invasion forces and gambles that friendly forces will be able to exhaust the aggressor in a war of pure attrition that could ultimately prove quite costly. This approach is not a safe bet against China, which has the world’s largest military and is actively pursuing its own version of attrition warfare with intelligent swarms.
If the Air Force were to de-emphasize air superiority and power projection in favor of air denial, this choice could severely erode the credibility of the U.S. deterrent and U.S. alliance commitments, and by extension, U.S. power and influence. Even Ukrainian leaders, who are focused on national survival as opposed to fulfilling global commitments, have long recognized the deterrent effect of bringing the fight to the adversary. Kyiv sought as early as April 2022 to bolster deterrence by taking the fight to the Russians. Ukraine continues to ask Western allies for more long-range firepower, including MQ-1C Gray Eagle drones, and, more recently F-16 fighter jets and long-range precision anti-tank artillery. Kyiv is now developing and fielding its own long-range drone, hardened against electronic attack to survive Russian air defenses. For its part, Russia is also seeking to reach deeper into contested Ukrainian territory to achieve its war aims. In recent months, Moscow has employed thousands of, fast, low-flying, long-range Iranian-built Shahed drones to counter the Ukrainians’ air denial strategy by overwhelming and exhausting Ukrainian air defenses. Both sides perceive that these long-range strikes have deterrent value – even if only symbolic. Russia expert Michael Kofman compared Ukraine’s drone strikes against Russian airfields in December 2022 to the Doolittle Raid on Tokyo on April 18, 1942. Although those U.S. bombers caused little damage, they demonstrated the Japanese homeland was vulnerable to attack and rallied U.S. public opinion.
The Air Force’s Drone Operations
Air denial is not an appropriate core mission for the U.S. Air Force, so there is no reason to think that Ukraine’s drone concepts and operations automatically apply to U.S. strategic requirements or operational needs. To shore up the Air Force’s combat credibility, the service must continue to rely on its advanced assets to project power and gain air superiority. As budget pressure has caused the number of those systems to decline, the Air Force will also need to bring more affordable mass to a conflict that could see levels of combat attrition on par with World War II. Analysis conducted by the U.S. Air Force, RAND Corporation, and our own work at the Mitchell Institute Center for UAV and Autonomy Studies suggests that large numbers of low-cost drones can play a critical role in reducing risk to Air Force missions while significantly raising the costs of aggression for peer adversaries. But these drones need the survivability, range, and sensors and payloads necessary to contribute to a blunt and hold campaign.
Arguably the most important characteristic of the Air Force’s next generation drones will be survivability. Next-generation drones will need to operate inside China’s anti-access/area denial environment to sense invasion forces and kill targets of opportunity, freeing up advanced inhabited assets to deliver firepower at volume. Runway independent drones, launched from rockets, or drones with the capability to operate from shorter civilian runways or dirt roads, provide a means to disperse from main operating bases that are likely to be targets of Chinese aircraft and missile attacks. Drones also will need survivability in the air, which can be achieved in two ways, both of which have value. One way is to field low-cost, “attritable” drones in large numbers so that they are easily replaced; Ukraine has adopted this approach, as has the Air Force, which needs affordable mass to augment its inhabited aircraft inventory. Another options is to build drones with low observable features that make them more difficult to detect. Low observability rises in importance if the drone is carrying precious sensors or payloads that need to survive to their targets, or if the drone is accompanying inhabited aircraft that need to preserve an element of surprise.
Range is another vital consideration. In Ukraine, short-range military and commercial drones have proven effective for artillery spotting and some direct attacks on the front lines. But sitting between Taiwan and China is 100 miles of ocean- the Taiwan Strait, and missile threats to U.S. air bases will require drones to base further away, in places like Japanese islands or perhaps the Philippines. Mitchell Institute research suggests drones may need minimum ranges of 1000 nautical miles or more just to effectively complete a mission inside the first island chain. That’s a far cry from the Bayraktar TB2’s 100 nautical mile range or the 46 minute flight time of a DJI drone.
The Air Force’s drones also need the right payloads. Bremer and Grieco suggest that the “mere threat” of a collision might be enough to keep advanced adversary aircraft out of drone-saturated airspace. But that is not a bet the U.S. Air Force should be willing to make. Drones need to do more than show up; they need low-cost sensors to detect targets, and both weapons-carrying drones and loitering munitions can help deliver the volume of fires needed to lay waste to Chinese invasion forces.
The requirement to bring mass to a highly contested battlespace also will create new challenges for both drone operations and logistics. The drones of Ukraine take commands from their operators via radio control or satellite links. The Air Force’s next generation drones will need to operate more independently from human control, incorporating autonomy to speed up decision-making, reduce reliance on vulnerable communications systems, and reduce burdens on human operators. Launching large numbers of drones in the Western Pacific also presents a serious logistics challenge to U.S. forces operating away from their home turf. And of course, all of these drone technologies need to be supported by software that can rapidly evolve, as both the U.S. and Russia compete to improve their ability to jam, spoof or shoot down drones as the conflict unfolds.
Building Next-Generation Drones for Great Power Conflict
Credibly preventing a Chinese invasion of Taiwan requires building a world-class force to rapidly attrit invasion forces, not a fielding a force on the cheap and planning from the start for a protracted, bloody fight. Of course, the Air Force’s drones don’t need the long-range, penetrating capabilities as its advanced inhabited aircraft – far from it. The most foundational advantage of any drone technology is that it has the potential to reduce costs in blood, treasure, and even political fallout. Fielding a next-generation combat drones and other innovative air and maritime technologies that didn’t flip the cost exchange ratio in favor of the U.S. would be a tremendous wasted opportunity. But the imperative to build large numbers of low-cost drones must be balanced with the strategic and operational demands facing the U.S. Air Force in the Indo-Pacific, which look very different from those now facing the Ukrainians.
Caitlin Lee leads the Center for UAV and Autonomy Studies at the Mitchell Institute for Aerospace Studies.