The latest bump in the relationship between Prime Minister Justin Trudeau and U.S. President Donald Trump played out on the public stage of an international summit this week. But the leaders of two of the world's closest allies have had their prickly exchanges before. Charlevoix, 2018: Aboard Air Force One, Trump tweeted that the prime minister was "very dishonest and weak" and withdrew American support for the joint leaders' statement at the summit conclusion. UN General Assembly, September 2018 Trump mentioned that he didn't like Canada's negotiating style or then foreign-affairs minister, Chrystia Freeland, who represented Canada in the NAFTA talks. During the rest of the assembly, Trudeau maintained a "quick but cordial" interaction with Trump. NATO, 2019: The host pool cameras focused on the group as they spoke candidly about Trump's lengthy interactions with reporters during bilateral meetings. The next day, Trump told reporters that Trudeau was "two-faced," but appeared to brush off what the prime minister said and noted that Trudeau was a "very nice guy."