London: US President Donald Trump branded Justin Trudeau "two-faced" and abruptly aborted his planned press conference at the NATO leaders' meeting, after the Canadian Prime Minister was caught gossiping and laughing to other world leaders about Trump's media appearances.

Speaking after a bilateral meeting, Trump applauded himself for his "two-faced" barb - which was also possibly a reference to the blackface scandal that threatened to derail the Canadian Prime Minister's bid for re-election this year.

"Well he's two-faced," Trump told reporters. "And honestly, with Trudeau he's a nice guy, I find him to be a very nice guy but you know the truth is that I called him out on the fact that he's not paying 2 per cent [on defence] and I guess he's not very happy about it."

Trump then cancelled his scheduled news conference at the end of the NATO summit, saying he had briefed the media many times during his two-day trip.