By all accounts, Vladimir Putin anticipated an easy war – the sort he might actually have got had he decided to go all the way in 2014, rather than confining himself to Crimea and the Donbass.

Instead, his woefully under-prepared armed forces have met ferocious resistance from the Ukrainians. Whilst the most likely outcome of a prolonged conventional war is still a Russian victory, however pyrrhic, some Western analysts are actually starting to suggest that Ukraine might actually win.

This is an optimistic assessment, but even as such it still implies a terrible price. For Putin’s complacent assumptions – paratroopers at the airport in Kiev, roll in the Rosgvardiya to pacify protesters – at least involved a minimalist approach to the conflict. Forced on to the back foot, he has proven just as willing to unleash indiscriminate bombing on European cities as on Syrian ones.

In response, western politicians and commentators are talking about prosecuting the Russian president and his soldiers for war crimes. But this poses a challenge when it comes to thinking about how this war might realistically end.

Even in the ideal Western scenario – an actual collapse of the Russian military operating in the Ukraine, precipitating the overthrow of Putin – we aren’t going to see Ukrainian or allied tanks rolling into Red Square. Putting the Nazis on trial required the complete conquest of Germany; that is simply not on the cards here.

That means that a path to peace likely involves creating an incentive for people currently involved in the regime, and therefore implicated in its crimes, to seek peace. This most obviously means a clear path towards easing sanctions in the event of Russian withdrawal, but it might also mean offering some sort of pass to individuals whom Western governments would much rather see at the Hague.

Otherwise, they risk lashing the elite of the Russian regime – who are the only people with any realistic prospect of changing it – even more tightly to Putin, even at a truly ruinous cost to the broader Russian nation and especially to Ukraine.

The prospect of making such compromises is gross; we are talking about people who negotiated a ‘civilian corridor’ and then, according to the International Red Cross, mined it. But whilst defeating the Russian army in the field would obviate much of the need, from here it still seems an unlikely prospect. If it doesn’t happen, the price of ending an ugly war might be an ugly peace.