The hugs of European leaders for Volodymyr Zelenskyy at a London summit this weekend could not have contrasted more sharply with the Ukrainian president’s dressing down in the White House on Friday. One upside of the Oval Office showdown is that it seems to have served as a galvanising moment — though there had been plenty already — in persuading Europe it must act. An outline strategy, if not yet a fleshed-out plan, has begun to take shape. But even greater speed and urgency is needed. However much they may hope to keep the US on board, European leaders and Canada must prepare for the real possibility that Donald Trump could cut off military support to Ukraine, leaving Kyiv and its non-US allies on their own.

The first step should be to accelerate European military support and funding as rapidly as possible, to strengthen Ukraine’s negotiating hand and ability to deter any future Russian aggression. More can still be done through joint European procurement to fill gaps in Ukraine’s armoury. European capitals should be ready, too, to dig even deeper into their own dwindling stockpiles; the front line of Europe’s security today runs through Ukraine.

In parallel, they should expand the model pioneered by Denmark of financing production by Ukraine’s arms industry, which has transformed its capabilities since 2022. That could enable a big boost in production of drones and missiles — helping to turn Ukraine into what the EU’s Ursula von der Leyen called an indigestible “steel porcupine”.