Undisciplined Ukrainian nationalists might act on their own. Tuesday’s brawl in parliament, when nationalist MPs dragged the Communist leader from the podium, and reports that separatists occupying a building in Luhansk may have a bomb, are evidence of the fluid situation. Fisticuffs are one thing, but bloodshed could transform the public mood. That is, after all, what happened in central Kiev six weeks ago.

If both sides in Ukraine were merely puppets of Great Power sponsors, the situation would be much less dangerous. Naturally, both the West and the Kremlin have their agendas. But neither side has control of radicals on the ground. The tension rattles Western stock markets, especially in Germany, and discourages talk of tougher sanctions – a plus for Putin. Any Russian intervention would put these back on the agenda. But without tangible pressure from Russian power, Kiev is unlikely to concede the demands of the Donetsk separatists for their own status. So agitators there might push the envelope further than the Kremlin would like.

The seven weeks until the presidential election offer extremists on both sides plenty of opportunity to make the running. Pro-Russians have no interest in a successful election; Ukrainian nationalists will stoke up tension as their best chance to rally voters. Such polarisation makes the chances of the Kremlin or Kiev achieving its aims peacefully virtually nil.