Trump is one of 32 leaders from the Western defensive alliance who are coming, along with the heads of more than a dozen partner countries. Dutch police have mounted their biggest ever security operation for the most expensive Nato summit so far, at a cost of €183.4m (£155m; $210m).

I am very curious to see how we are heading towards the NATO summit at the end of June,” he remarked. “Whether we will still be talking about NATO in its current form or whether we will have to establish an independent European defence capability much more quickly.