As the Ukraine war on the ground becomes bogged down in a seemingly unbreakable stalemate, and public discontent in both Russia and Ukraine grows, the governments in Moscow and Kyiv are escalating the conflict in the air in an effort to change the situation to their advantage. This will lead to increased civilian casualties on both sides. It also increases the risk of clashes that will draw NATO and Russia into direct conflict—though it is also quite possible that the war will end in an inconclusive ceasefire and a frozen conflict.

Two developments in May emphasized the danger of escalation. In response to Ukrainian drones flying over the Baltic States to attack targets in Russia, Moscow accused the Baltic governments of complicity and threatened an attack on Latvia. NATO claimed (implausibly, and with no evidence) that the drones had been redirected over the Baltic states by Russian jamming; but it seems at least equally likely that Ukraine was using Baltic airspace, protected by NATO, to get as close as possible to its targets near St. Petersburg before encountering Russian air defenses.

And in response to increasingly damaging Ukrainian drone and missile attacks on Moscow and Russian energy infrastructure (which Russia believes are aimed with the help of Western intelligence), the Russian government warned that it would start attacking Ukrainian headquarters in Kyiv, and warned Western officials and citizens to leave the city. This was widely taken as an indication that Russia is going to attack these targets with Oreshnik ballistic missiles—something that it has refrained from doing so far, presumably out of fear that casualties among NATO advisers would lead to drastic escalation by the West.

For the moment, both sides have stepped back from the brink. NATO has begun to shoot down Ukrainian drones over the Baltic states; and while Russia has increased its attacks on Kyiv, it has not yet made good on its threat to launch strikes that would cause Western casualties.

The danger however remains extremely serious. The Ukrainian air campaign against Russia is beginning to do serious damage (and of course the Ukrainians feel entirely justified, since their infrastructure has been under Russian attack for the past three years). As a result of this and tiny Ukrainian advances on the ground in the Donbas, Western official and unofficial figures are beginning to declare again that Ukraine can “win.”

If by this they mean that Ukraine could fight Russia to a standstill and bring about a compromise peace, they are almost certainly correct. Indeed, Ukraine, with Western help, has already demonstrated its ability to do this. If, however, these supposed friends of Ukraine mean that Ukraine can defeat Russia and bring about the fall of the Putin administration and system, they are being profoundly foolish. Recent Ukrainian advances on the ground in the Donbas have been just as small as Russian advances in the opposite direction. Indeed, this is hardly a matter of “advances” at all. The omnipresence of drones has created a “killing zone” more than a dozen miles wide in which only tiny groups of soldiers can operate, occasionally occupying an individual building or ruined hamlet, and often then having to scuttle quickly back to their own lines.

It is equally foolish to believe that limited aerial bombardment will lead to a revolt against Putin. Much heavier Russian bombardment of Ukraine over a much longer period has not broken the will of the Ukrainian people to resist. In fact, relying purely on aerial bombardment of civilian targets as a strategy has never worked, whether employed by the Luftwaffe, the RAF Bomber Command, or the USAAF.

It is true that war weariness is growing in both Ukraine and Russia, and this is leading to increased calls on both sides for a compromise peace. The problem is that among hardliners on both sides this is leading instead to increased pressure to break the stalemate by drastic escalation.

Pressure on the Ukrainian and Russian governments is increased by their increasing shortages of soldiers. Casualties on both sides have been enormous—higher for the Russians in terms of numbers, but higher for the Ukrainians in proportion to their much smaller population. In Ukraine, this is leading to demands both from the West and from the Ukrainian army finally to start conscripting men from the age of 18; in Russia, to pressure to abandon reliance on paid volunteers and launch mass conscription. Both moves would be bitterly unpopular with their respective populations.

The risk is that faced with this impasse, hawks on both sides will enter into a de facto collusion to try to break the stalemate by dragging NATO into the war. Ukrainian hard-liners may believe that only direct NATO involvement can compel a Russian surrender. Russian hard-liners may believe that a direct confrontation with the West will both bring the Trump administration back into a peace process that it is walking away from and terrify the Europeans into agreeing to peace on Russian terms.