There are two important precedents that I want to see set at the end of the war in Ukraine:
First, you cannot expand your territory through invasion. All borders are reset to their pre-war locations, including Crimea. I thought we’d set that one last century, but it’s important because if a peace settlement allows an aggressor to keep even some of their gains then that incentivises future invasions.
Second, those who benefitted from the war or had the power to stop it cannot escape responsibility. Oligarchs who propped up the Putin regime, including folks like Elon Musk (if this week’s reports are true), get their assets seized to pay for reconstruction. You don’t get to send poor people to die and sit back in luxury. Hopefully we learned after the Second World War that things like the Treaty of Versailles were a bad idea, but I suspect the 1930s might have played out differently if the Kaiser and the aristocracy had had to pay the war reparations personally and lost their control over the country.
I doubt there’s political will for the second because the people who might be able to enforce it don’t want the precedent to be applied to them in the future.