Mr Trump's demand came a day after Angela Merkel, the German chancellor, reiterated Germany's intention to increase spending to two per cent during her first visit to the White House under the new administration.

The spat marked the beginning of what may well be the most important week of Mr Trump's young presidency.

On Monday, James Comey, the director of the FBI, will testify at a public hearing as part of an investigation by the House Intelligence Committee in Congress on Russian meddling in the US election, including potential connections between Mr Trump’s inner circle and the Kremlin.

It will be the first time that Mr Comey, along with Mike Rogers, the director of the National Security Agency, have spoken publicly since Mr Trump took office on the issue that continues to dog his presidency.