Over the past six months President Donald Trump has been all over the place on Ukraine. He said he could end the war in 24 hours. Then, while negotiating with Russia, he threatened to cut off the supply of weapons to Ukraine. In the past week he has signalled a new enthusiasm for supporting Ukraine. His spectacular pivot involves ambiguity, theatre and cynicism. Yet it creates a pathway for Ukraine and its supporters to stabilise a weakening position. They must take it.