In the end, the long charm offensive by Canadian Prime Minister Justin Trudeau to avoid the ire of U.S. President Donald Trump failed just hours after success seemed closest, with Trump raining insults as Trudeau closed what seemed like a triumphant global summit. Aside from the escalated risk of a trade war, Trump's blistering personal attack on Trudeau poses domestic economic and political risks for the Canadian prime minister, who has stuck to a conciliatory stance in the face of U.S. threats on NAFTA and other bilateral trade cases. "PM Justin Trudeau of Canada acted so meek and mild during our @G7 meetings only to give a news conference after I left saying that, 'US Tariffs were kind of insulting' and he 'will not be pushed around.' Very dishonest & weak," Trump tweeted as he flew to a Singapore summit on North Korea. The attack shattered any hope that Canada could avoid U.S. tariffs on steel and aluminum or renegotiate the North American Free Trade Agreement by virtue of the charm, patience or measured response it has extended to Trump since he took office.

President Donald Trump and Canadian Prime Minister Justin Trudeau hold a meeting on the sidelines of the G7 Summit in La Malbaie, Quebec, Canada, June 8, 2018. Saul Loeb | AFP | Getty Images

Trudeau's office, reeling from the abrupt Trump reversal hours after the two men had joked and smiled their way through a fractious G-7 meeting, said only that Trudeau had said nothing in his news conference that he hadn't said before. "Canadians are polite, we're reasonable, but we also will not be pushed around," Trudeau had told reporters as he reiterated that Canada would retaliate against U.S. tariffs on steel and aluminum, adding Trump's rationale had been insulting.

'Stabbed in the back'