Putin has been winning in Ukraine. The country is nowhere near joining NATO, a western goal only a few years ago, and Russia’s annexation of Crimea is a geopolitical fact. Putin is also a master in using military force in ways that don’t quite cross over to hot war. Western powers have been signalling that they won’t allow a new invasion of Ukraine to go unpunished. But judging when to act, and how, is crucial. The pompous, yet vacuous rhetoric used by the west risks pushing the conflict over the line into a military one, for which there is no strategy or exit plan, writes Hew Strachan.

On December  12 the foreign ministers of the G7 states met in Liverpool to avert the danger of a possible Russian invasion of Ukraine. They were a bit late. The war has been going on for well over seven years. In 2014 Russia annexed Crimea and occupied parts of the Donetsk and Luhansk regions of the Donbass in Ukraine’s south-east. Sporadic fighting and a steady if sustainable flow of casualties have continued ever since.