The Trump administration could make the bombshell declaration as senior defence officials at the Pentagon try to force allies to hit Nato's 5 per cent spending pledge.

A senior official in the US reportedly told The Telegraph that Britain will receive "special attention" from Washington in its attempts to get Nato up to the spending figure.

The source said: “I would expect the UK to receive special attention because it has so much potential.

“We will therefore continue efforts to incentivise and enable the UK to step up in a major way.”