White House press secretary Sean Spicer made the announcement at a briefing.

May is overseeing Britain's departure from the European Union, or Brexit, which was approved in a swell of anti-establishment fervor that has been likened to that which propelled Trump to the US presidency.

May congratulated Trump after he was sworn in on Friday.

She said she thinks Trump recognizes the importance of NATO even though days ago he called the military alliance obsolete.