Prime Minister Justin Trudeau is expected to travel to London next month where recent comments by French President Emmanuel Macron questioning the viability of the alliance threaten to overshadow a celebration of NATO's 70th birthday.

NATO foreign ministers are meeting in Washington to celebrate the alliance's 70th anniversary amid rifts between members over security and trade issues.

The NATO secretary general credited U.S. President Donald Trump with compelling allies to spend more on defense.

During moments that were visible to the press, Trump often separated himself from most of his counterparts, particularly those with whom he has had public disagreements, such as British Prime Minister Theresa May, German Chancellor Angela Merkel and Canada’s Justin Trudeau.

In a letter sent on June 19th, Trump criticized allies such as Canada who haven't increased their defence spending as promised, and cited the United States' "growing frustration."