Jens Stoltenberg listed Canada's deployment of hundreds of troops to Latvia and Iraq as critical to helping protect North America and Europe and strengthening the alliance.

The footage, which was shot by the British host's pool camera, has since spread across the internet, with observers suggesting Trudeau and the other leaders were mocking Trump and wondering how the mercurial U.S. president will react.

Trump suggested Trudeau and Mexico's president "will get tired'' of further delays.