The deal agreed by Vladimir Putin and Petro Poroshenko in Minsk yesterday provides a ray of hope that the conflict in eastern Ukraine might be moving towards a settlement. But it would be foolish to view the pact more optimistically than that. After a testy 16-hour negotiation, the Russian and Ukrainian presidents have at least settled on a framework to end the fighting that has taken more than 5,000 lives. However, a similar agreement signed in the Belarusian capital in September swiftly collapsed. And any optimism about Minsk II requires a leap of faith that Mr Putin has suddenly become serious about repairing his relations with Ukraine and the west.

Central to the deal is a ceasefire that comes into force on February 15. It would create a demilitarised corridor separating Ukrainian and pro-Russian forces by up to 140km. As ever, there are plenty of loose ends that provide pretexts for renewed conflict should Mr Putin choose to blow hot again. For instance, the text allows for two more days of fighting and two weeks for the pullback of heavy weapons. The status of surrounded Ukrainian troops in the strategically important town of Debaltseve is worryingly unclear.

Even if both sides put an end to hostilities, that still leaves the problem of finding a more lasting settlement. yesterday’s pact sketches the outlines of a comprehensive political deal that would see Kiev devolving power to the pro-Russian regions of Donetsk and Lugansk. And here, too, there is much that Mr Putin can exploit to his own advantage if he so desires.