Trying to work out Vladimir Putin’s intentions in Ukraine has now become the critical task of western diplomacy, and one made harder by the distractions faced by political leaders in Europe and America.

For weeks Russian troops have amassed on the border with eastern and now northern Ukraine, raising fears of an imminent invasion. Moscow denies any such intention and it is, indeed, hard to discern where the advantage would be to Russia to immure itself in a war with its neighbour.

The most benign explanation is that President Putin is engaged in his favourite pastime of disconcerting western governments, to drive home his demand that Nato encroachment eastwards should go no further. Last week’s talks between Russian and Nato officials failed to reach any agreement, though Mr Putin may feel his point has been made without needing to resort to anything more drastic. But no-one can afford to take that risk. He is good at sensing weakness abroad and may feel that all the strong words about Russia facing serious consequences should its troops invade are just so much hot air.

The mess over the US withdrawal from Afghanistan damaged President Biden who increasingly resembles a lame duck; Boris Johnson is assailed by domestic considerations and fighting to stay in office; President Macron faces an election in three months’ time; and the Germans have a new government and are beholden to Russia for energy supplies. Mr Putin may think this is the time, therefore, for more than just sabre-rattling.

American analysts have received credible intelligence about the potential for what is known as a “false flag” operation, whereby saboteurs target proxy Russian forces in the country giving a pretext for an invasion. Similar activity was seen ahead of the invasion and annexation of Crimea in 2014, which led to the imposition of sanctions on Moscow. But these made no difference and the peninsula remains in Russian hands.

Mr Putin is unlikely to take seriously the threat of yet more sanctions and must be aware that there is little or no appetite for Western military involvement in Ukraine. This may all be part of a game of geopolitical bluff that Mr Putin is playing or the precursor to an imminent invasion. Western leaders need to be ready for the latter and yet it is by no means clear that they are taking this threat seriously enough.