Last Monday, the Guardian’s central and eastern European correspondent, Shaun Walker, sat down in Kyiv to interview the Ukrainian president, Volodymyr Zelenskyy.

The conversation, Walker explains, was dominated by what Zelenskyy hoped to achieve in any upcoming talks on a ceasefire deal in Ukraine. The president outlined his red lines, too: that the US would have to be involved in some way in securing Ukrainian security once the fighting stopped; and that any negotiations over its future would have to involve Ukraine itself.

Yet as Michael Safi hears, barely two days later Donald Trump blew all of that out of the water. The US president said he had called Vladimir Putin directly and begun to discuss how the war in Ukraine might end.

If the announcement shocked leaders in Kyiv and across Europe, worse was yet to come – as statements from senior Trump officials began to call into question the very future of any US support for Europe’s security, undermining an alliance that came into existence nearly 80 years ago.

So, what next for Ukraine? And if the US does intend to withdraw its support for its allies in Europe, how will the continent defend itself in future?