It was meant to be a landmark summit - a celebration of NATO, and the Alliance's success in helping to secure peace in Europe for 70 years.
But the meeting of world leaders ended in acrimony with Donald Trump calling the Canadian leader "two-faced", before cancelling a planned news conference and flying home.
The cause was a video that appeared to show Justin Trudeau gossiping about the US president with - among others - Boris Johnson.
The fallout from that - and another spat with the French President Emmanuel Macron - overshadowed talks that were supposed to tackle the most significant threats to security in Europe and the world.
Sky's foreign affairs editor Deborah Haynes reports.
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