You don’t have to like Vladimir Putin, or doubt that he’s a nasty piece of work, to recognise that the Russian president’s reaction to the crisis in Ukraine is largely justified. The promise that Russia managed to extract from the West, as it watched its old empire crumble, was that NATO would not expand eastward and that the Baltic states and Poland would not be absorbed into the EU. Not only have Nato and the EU broken that promise, they have even sought to bring Ukraine – for centuries seen as umbilically tied to Russia – into the western fold. The West has tried to influence elections in Ukraine. It has backed the overthrow of a democratically elected president. Putin isn’t being expansionist: he just wants Ukraine to remain a non-aligned buffer zone between Russia and the West. He couldn’t survive the national humiliation of it becoming yet another western outpost. So cut him some slack: we need more diplomacy and fewer threats of reprisals.

That’s the voice of the non-interventionists but haven’t they been duped? Is a man who sends undercover troops into Crimea and then swears that they are locals defending their homeland really to be trusted? Ask the people of Georgia, whose country has been carved up by Putin, whether they think he has no interest in expansion. Ask most Ukrainian citizens, yearning for western democratic freedoms, whether Putin has a right to deprive them of those freedoms in the name of some bogus historical affinity. Of course autocrats have their reasons, but are they reasons we have to accept as justifiable? There is no moral equivalence between the ambitions of a repressive state and those of a repressed people. Putin needs to know that there is a line he cannot cross. Otherwise you can be absolutely sure he will cross it.