But his demand was swiftly rejected by German Defence Minister Ursula von der Leyen, who said on Sunday that “there is no debt account at Nato.”

She added: “Defence spending also goes into UN peacekeeping missions, into our European missions and into our contribution to the fight against IS terrorism.”…

Ivo Daalder, the former US ambassador to Nato, also took issue with Mr Trump’s claims and replied directly to the president on Twitter.

“I’m sorry, Mr President but that is not how Nato works,” he said, pointing out that Nato spending was not a “financial transaction” between countries but a joint commitment to spend two per cent of GDP on defence.