As Russia’s war against Ukraine grows bloodier and more destructive, and with the expectation of further escalation, there have been calls from current and former officials – including Ukrainian President Volodymyr Zelenskyy, members of the U.S. Congress, former North Atlantic Treaty Organization (NATO) commanders and various media figures – for the United States or NATO to establish a no-fly zone to protect Ukraine from Russian air attacks. President Joe Biden and the NATO alliance as a whole have stated clearly that a no-fly zone over Ukraine is not an option. The U.S. government and the NATO foreign ministers have taken this measure off the table because establishing a no-fly zone, as with other forms of direct U.S. or allied military intervention, means going to war with Russia. Russian President Vladimir Putin has said he would view countries involved in policing a no-fly zone as “participant[s] in a military conflict”.
What is a “no-fly zone”?
A no-fly zone is a region of airspace from which certain aircraft are coercively excluded, often as a measure to protect civilians living below. As Crisis Group’s Europe and Central Asia Program Director Olga Oliker noted on Twitter, a no-fly zone represents “a decision to shoot at planes that fly in a given area”. A no-fly zone is not merely declared, it is established and maintained through the credible threat of shooting down aircraft; this means firing on hostile aircraft should they fly in the zone.
Enforcing a no-fly zone may also involve attacking aircraft on the ground, airfields from which those aircraft take off or other support infrastructure. Although no-fly zones have varying parameters, they typically entail the suppression or destruction of enemy air defences, including surface-to-air missiles and radar facilities, to prevent attacks on the aircraft enforcing the zone. In other words, implementing a no-fly zone requires the enforcing state or states to establish air supremacy and for this, they have to be prepared to strike enemy forces.
Where have no-fly zones been implemented?
The modern concept of a no-fly zone emerged in the 1990s. Following the 1991 Gulf War, the U.S., UK, France and Turkey established two no-fly zones over Iraq to protect civilians, Kurds in the north and Shia in the south, from attacks by the government of Iraq. In the period from 1991 to 2003, when the zones were enforced, coalition aircraft were fired upon by surface-to-air missiles, struck air defence targets on the ground and engaged in aerial combat with Iraqi aircraft.
During the Bosnian War, atrocities against civilians spurred the U.S. and NATO allies to impose a no-fly zone from 1993 to 1995. The UN Security Council provided the mandate for the operation, banning fixed- and rotary-wing aircraft from Bosnian airspace and authorising member states to use “all necessary measures” to “ensure compliance with the ban on flights”. The extent to which the no-fly zone protected civilians in Bosnia is debated: parties to the conflict continued to commit atrocities on the ground, including Bosnian Serbs’ genocide against Bosnian Muslims at Srebrenica while the no-fly zone was in place.
The 2011 NATO military intervention in Libya, Operation Odyssey Dawn/Operation Unified Protector, included a no-fly zone but went further. The UN Security Council mandated an intervention to protect civilians and authorised, in addition to a no-fly zone, “all necessary measures … to protect civilians and civilian populated areas under threat of attack”. The NATO-led coalition that operated under the mandate interpreted it broadly. While its operations may have helped prevent a feared massacre of civilians in Benghazi, they involved extensive targeting of Libyan government forces on the ground and ultimately assisted Libyan rebels in overthrowing Muammar Qadhafi. The latter in particular was repeatedly criticised by Russia and other countries on the Security Council at the time as going beyond the UN mandate.
The Obama administration extensively debated establishing a no-fly zone in Syria, particularly between 2015 and 2016, to protect civilians and opposition forces from the attacks of the Syrian government. During her presidential campaign in 2016, former Secretary of State Hillary Clinton advocated for the establishment of a no-fly zone to protect Syrians from air attacks directed by Damascus and Moscow, following Russia’s direct intervention in the war in 2015. The administration did not implement these proposals, in part because officials did not think a no-fly zone would in fact protect civilians from Syrian government or Islamic State (ISIS) attacks, and also because doing so would require U.S. forces to (in the words of President Barack Obama) “militarily take over a big chunk” of Syria. Following Russia’s intervention in the conflict, the risk of direct confrontation between U.S. and Russian forces was an additional concern.
Nonetheless, U.S. military operations against ISIS in Syria have resulted in the creation of de facto no-fly zones in the east of the country as the U.S. and Russian militaries have established deconfliction zones to avoid potential armed friction. These zones include a 55km area around the Tanf garrison in south-eastern Syria.
Notably, in none of these cases did the U.S. attempt to coercively establish a no-fly zone against a near-peer military with sophisticated air defences, as some have suggested doing over Ukraine.
What would a no-fly zone for Ukraine entail and what are the risks?
Those advocating for a no-fly zone over Ukraine have not clarified the precise contours of such a military operation, including whether it would be limited to excluding Russian aircraft from Ukrainian airspace or, as occurred in Libya with different actors, also entail attacks against Russian ground forces. In any event, a no-fly zone would likely require not merely the threat of the use of force, but actual U.S. and/or allied attacks on Russian forces. To be very clear, a U.S. no-fly zone over Ukraine would necessitate a direct military confrontation with Russia, and as noted above, President Putin has said he would regard this as bringing the U.S. into the conflict.
If history is any guide, the establishment of any no-fly zone would likely involve the suppression of Russian air defences - that is, strikes on Russian forces. Given the range of some Russian surface-to-air missiles, it is possible that these air defences could be located in Russia itself, and thus suppressing them might require strikes on targets in Russian territory. Moreover, for the no-fly zone to be effective in closing Ukraine’s airspace, the U.S. or its allies would have to be prepared to shoot down Russian aircraft. They would also need to be prepared to maintain the no-fly zone for the duration of the war. Even a limited “humanitarian no-fly zone” over western Ukraine, a concept endorsed by former NATO Supreme Commander General Philip Breedlove, would likely require many of these actions and necessitate a willingness by the U.S. or NATO to use military force against Russia. It would also appear to step over the red line that Putin laid out in his pronouncement on no-fly zones.
NATO’s controversial 1999 air war in Kosovo is instructive as to the nature of operational risks of such civilian protection undertakings. Operation Allied Force was launched in response to human rights abuses by Yugoslavia against ethnic Albanians in Kosovo, and, despite the clear superiority of its forces, NATO was unable to establish air supremacy during the 78-day air campaign. That intervention was undertaken against a force that did not resemble anything approximating a near-peer military. Establishing a no-fly zone in the face of Russia’s much more significant assets would entail much greater effort and risk, potentially fuelling an escalatory cycle in the pursuit of air supremacy against a near-peer adversary.
It is also not fully clear what establishing a no-fly zone would accomplish by itself. So far, Russia has yet to fully utilise its air force in the war, and has instead relied more heavily on artillery, rockets, and cruise and ballistic missiles – the effects of which have been devastating for Ukraine’s cities. As pointed out in this useful explainer, published by two former U.S. air force officers in War on the Rocks, this may be in part because Russia’s army thus far controls only limited territory, and cannot establish air defences over territory that Ukraine controls. Ukraine therefore continues to conduct air operations against Russian forces. Thus, it is unclear at this stage whether removing Russia’s air force from the conflict would fundamentally alter the overall military balance between Ukraine and Russia.
Still, it is possible that Russia is prepared to deploy its air force more aggressively as the conflict continues. Moreover, even if the Russian air force continues to be under-utilised, U.S. or NATO warplanes deployed over the fighting would be at risk not only from Russian air defences, but also from friendly fire from Ukrainian forces, particularly given the transfer of large quantities of shoulder-fired surface-to-air missiles from NATO members to Ukraine.
Beyond the operational risk, Putin’s announcement about how Moscow would view the establishment of a no-fly zone makes abundantly clear that the United States or NATO’s seeking to deprive Russia of airpower in the conflict would be an extraordinarily dangerous gamble with unclear returns. Given the risk of escalation between the world’s largest nuclear powers from any military confrontation, the Biden administration, the UK government and the NATO secretary general have unsurprisingly and wisely rejected proposals to establish such a zone. As explained here, in the event of a military clash, the risk of nuclear use would become worryingly high. That risk must be avoided. The human costs of Russia’s war on Ukraine are heartbreaking; the costs of a nuclear war are unfathomable.
Olga Oliker, Program Director, Europe and Central Asia, Brussels; Michael Wahid Hanna, Program Director, U.S. and Brian Finucane, Senior Adviser, U.S..