Past threats former president – and present Russian ones – have spurred Europe to invest in self-defence, but as conflicts rise the alliance still looks vital

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Politeness and convention dictate that European leaders try to sound noncommittal when asked whether a Donald Trump presidency would hurt Nato. But despite the rhetoric about “Trump-proofing”, Nato cohesion will be at risk from a hostile or isolationist Republican president, who has previously threatened to leave the alliance if European defence spending did not increase.

“The truth is that the US is Nato and Nato is the US; the dependence on America is essentially as big as ever,” said Jamie Shea, a former Nato official who teaches at the University of Exeter. “Take the new Nato command centre to coordinate assistance for Ukraine in Wiesbaden, Germany. It is inside a US army barracks, relying on US logistics and software.”