Credit: Kristopher Wilson via Wikimedia Commons

Online Exclusive 03/9/2022 Essay

A No-Fly Zone in Ukraine? The Perils of Escalation Should Convince Us Otherwise

As the Russian war of aggression in Ukraine unfolds, we have witnessed multiple calls for the West to implement a no-fly zone. On the front lines, Ukrainian President Volodymyr Zelenskyy has pled for NATO to establish a no-fly zone over Ukraine to help protect civilians and Ukrainian sovereignty.1 In the United States, Republican Congressmen Roger Wicker and Adam Kinzinger supported the idea in order to, quoting the latter’s tweet, “give the heroic Ukrainians a fair fight.”2

Other U.S. officials have ruled out such a military commitment as an option. White House Press Secretary Jen Psaki sums up the concern this way: Setting up and enforcing a no-fly zone “is definitely escalatory, [a move that] would potentially put us in a place where we are in a military conflict with Russia.”3

As civilian casualties mount and the humanitarian crisis deepens, how do we ethically evaluate the decision of whether or not to implement a no-fly zone in Ukraine? What criteria are most important to think through the choice? To answer these questions, I turn to jus ad vim, the set of moral principles governing the decision to use limited force.4 The novel probability of escalation principle requires that imposing a no-fly zone be accomplished without escalation to a wider war with Russia. Taking into account the evolving situation, this essay argues that despite having a just cause to protect Ukrainian civilians and assist Ukraine in checking Russian aggression, concerns over escalation tilt the scales in favor of saying “no” to a no-fly zone.

A No-Fly Zone Is a Military Commitment, but Not All No-Fly Zones Are the Same

A no-fly zone is a coordinated military activity designed to secure a piece of territory and airspace by denying access to an adversary’s aircraft.[note]See Karl P. Mueller, “Denying Flight Strategic Options for Employing No-Fly Zones,” RAND Project Air Force (Rand Corporation, 2013), available at:
and Alexander Benard, “Lessons from Iraq and Bosnia on the Theory and Practice of No-fly Zones,” Journal of Strategic Studies 27:3 (2004), pp. 454–78.[/note]

As a strategic military tactic, no-fly zones have only been implemented on three occasions: Iraq (1991–2003), Bosnia (1993–1995), and Libya (2011).5 There were calls to implement no-fly zones to protect civilians in Syria (2013) and the Yazidi from ISIS advances in Iraq (2014), but these calls went unheeded.

It is important to observe that there are different kinds of no-fly zones, with different strategic objectives. “Protective zones of aerial exclusion” are intended to prevent vulnerable civilian populations from being targeted indiscriminately from the skies (Iraq, Bosnia, and Libya all started off this way). “Coercive no-fly zones” put pressure on a specific regime to comply with specific demands (Iraq morphed into this kind). Finally, “rebel-aiding no-fly zones” provide military assistance to groups seeking to gain control of a political and geographical space (Libya escalated into this type).6 The requested Ukraine no-fly zone would be a variation on the first and third types—what one might call “a sovereignty sustaining no-fly zone.”

Pursuing no-fly zones has two phases, both of which entail the use of kinetic force.

First, setting up a no-fly zone means engaging the enemy to gain control of the skies in order to protect civilians from aerial harm. The protective no-fly zone in the Libya case illustrates exactly what this process entails. Then U.S. Secretary of Defense Robert M. Gates explained in early March 2011, when the U.S. was contemplating how to contain Libyan aggression against civilians and rebels:

“A no-fly zone begins with an attack on Libya to destroy the air defenses. That’s the way you do a no-fly zone. And then you can fly planes around the country and not worry about our guys being shot down. But that’s the way it starts.”7

A no-fly zone in Ukraine would require Western forces to destroy Russian air defenses in order to have total control over the skies. This would prevent Russian aircraft the ability to strike Ukrainian targets as the war wears on, leveling the playing field on the ground and providing a layer of protection to civilians. There are no guarantees that this goal would be accomplished without significant costs to Western pilots. And the major risk, which we return to below, is escalation to a wider (potentially nuclear) war.

Second, assuming aerial domination is achieved (a big “if” in this case), next comes the phase of maintaining the no-fly zone. This entails patrolling the skies for an undetermined period of time, periodically engaging any enemy attempts to break through. The no-fly zones mentioned above lasted for a cumulative twenty-five years, which involved daily sorties and periodic engagement with enemy forces.

If protecting civilians is a major goal of a no-fly zone, this can only ever be partially accomplished simply by patrolling the skies: civilians would remain vulnerable to Russian ground forces.8 Bosnia is an example of the imperfect layer of protection no-fly zones provide. Thus, while protecting civilians in an absolute sense might not be the stated goal, once a no-fly zone is in place it would be tempting to use that aerial domination to further effect. The no-fly zone in Iraq was expanded to include a “no-drive zone” that prevented Iraqi military operations in the south.9 In the Ukraine case, a protective no-fly zone would almost inevitably morph into a no-fly zone focused on helping Zelenskyy’s Ukrainian government regain sovereignty. Such a shift would require targeting the forces shelling Ukrainian cities, and maybe Russian supply lines as well.

No-Fly Zones and the Risk of Escalation

A hypothetically successful no-fly zone in Ukraine would protect civilians and buttress Ukrainian sovereignty by providing just enough military advantage to turn the tide of the war on the ground, and in doing so, open the door for negotiations that could resolve the conflict. But there are huge risks.

Despite being protective in intent, no-fly zones have a natural tendency toward escalation—with a track record to prove it. This should not be overlooked. My work on the ethics of limited force has highlighted the importance of escalation in ethically evaluating no-fly zones.10 There are two types of escalation to consider.

The first type of escalation is by choice of the initiator of the no-fly zone. Iraq and Libya are both instances where the implementor of the no-fly zone escalated the level of force to pursue wider ends. In Iraq, the no-fly zone began as a protective no fly-zone, developed into a coercive no-fly zone, and then escalated from a failed no-fly zone to a full-blown preventive war.11 In Libya, the shift was from a protective to rebel-aiding no-fly zone to overthrow the Qaddafi regime.12 It is also worth mentioning that the Bosnia no-fly zone did not solve the problem of Serbian aggression in the region in the long run; witness the Kosovo conflict.

A no-fly zone in Ukraine would inevitably risk this kind of escalation, too. If past is precedent, mounting civilian casualties, sunken costs, and the fear of losing face if the initial goals are not achieved will weigh on policy makers’ minds and influence decisions about whether to expand target lists,13 de-escalate, or cut losses at the negotiating table.14

A no-fly zone is “a way to not do nothing,” that is, for a state or groups of states to do something to protect civilians that does not involve committing to waging war. But there is a risk they could be drawn into a wider war.5 Thus, a second kind of escalation is “retaliatory escalation.” Russia could, and likely would, view a NATO-led no-fly zone as a declaration of war and react by attacking Western targets beyond Ukraine. As many have noted, Russia has a military far better equipped than those countries that were subject to previous no-fly zones, meaning the consequences of attempted implementation would likely be global.15 Putin has threatened nuclear escalation if NATO gets involved militarily.16 Choosing to impose a no-fly zone, warned both a top general and the U.K. Defense Secretary, could very likely lead to a nuclear World War III.17

Supporting Ukraine by Other Means

The moral principles of jus ad vim, by putting an emphasis on the risk of escalation, gives clear moral counsel in this case. While there is just cause to set up a no-fly zone in Ukraine, the risk of wider war with Russia outweighs acting on just cause because the probability of escalation, and the consequences this entails, is simply too high.

Nonetheless, the choice not to set up a no-fly zone could be interpreted as the West doing too little in the face of Russian aggression and Ukrainian suffering. Pundits have been quick to compare the Russian invasion of Ukraine to the Soviet invasion of Hungary in 1956 and Czechoslovakia in 1968, where the West did not militarily support popular uprisings.18 Embattled Ukrainian President Zelenskyy linked—causally and morally—NATO’s refusal to pursue a no-fly zone with increased civilian deaths in Ukraine.19

However, the choice not to pursue a no-fly zone does not mean that NATO is abandoning Ukraine altogether. Instead, the choice is doing something important; namely making a difficult ethical choice to avoid the unpredictability of a wider war and thus spare civilians—including more than one million Ukrainians that have already fled—the ravages of Russian escalation beyond Ukraine.20

Moreover, unlike 1956 and 1968, the West is actively supporting Ukraine and can still do more while avoiding the perils of escalation. Already, many countries around the world, led by members of NATO, have imposed unprecedented economic sanctions on Russia.21 They have also provided military aid and weapons to help Ukraine sustain its sovereignty.22 Politically, Ukraine could be aided by the EU fast-tracking Ukraine’s EU application. Finally, these governments can provide support by demanding legitimate humanitarian corridors away from the aggressor’s borders, for civilians to escape cities under siege and by opening their own borders to Ukrainian refugees

While there is a moral imperative to do something, deliberations about the proper response must consider the risks of a wider war or nuclear escalation. In the end, the perils of escalation rule out a no-fly zone.23 In the meantime, Europe and the rest of the world must give those options short of Western military intervention a chance to succeed and continue to support Ukraine in those ways that are morally acceptable within the jus ad vim framework.

—Daniel Brunstetter

Daniel Brunstetter is Associate Professor of Political Science at the University of California, Irvine. He is the author of numerous books and article on the ethics of war, including Just and Unjust Uses of Limited Force (with Oxford University Press), which revisits the major wars animating contemporary just war scholarship (Kosovo, Afghanistan, Iraq, the drone ‘wars’, and Libya) through the lens of limited force to tease out an ethical account of force-short-of-war.