The G-7 summit in Quebec went very poorly, and it concluded with Trump lashing out at the host, Canadian Prime Minister Trudeau, in response to Trudeau’s restatement of his objections to the steel and aluminum tariff increases imposed earlier this month. Trump’s top economic adviser attempted to justify the president’s actions as a way of sending a message to North Korea ahead of Tuesday’s summit in Singapore:

“POTUS is not gonna let a Canadian prime minister push him around,” Trump’s chief economic adviser, Larry Kudlow, said on CNN’s “State of the Union.” “He is not going to permit any show of weakness on the trip to negotiate with North Korea.”

“So this was about North Korea?” CNN host Jake Tapper asked.

“Of course it was, in large part,” Kudlow said. “Kim must not see American weakness.”

If the president feels the need to lash out publicly at a close ally over perceived slights, that doesn’t convey strength or confidence or whatever it is Kudlow thinks Trump showed. It cannot possibly benefit the U.S. in negotiations with North Korea if the president is and is seen to be as unreliable and prone to picking fights with close allies for no good reason. It does not reassure our East Asian allies that Trump has gone out of his way to strain relationships with other close allies, and it can only encourage the North Korean delegation to see how easily Trump flies off the handle and how ineffective he is at negotiating on behalf of the U.S. Insofar as the G-7 debacle weakened U.S. relations with its allies, it distracts attention from and relieves pressure on North Korea. It also reconfirms what we have known all along: Trump has neither the temperament nor the understanding to bridge the huge gap between the U.S. and North Korea when he cannot even manage relatively minor disagreements with our closest allies.

The president’s fixation on not appearing “weak” is what led to the embarrassment in Canada, and it is likely to derail talks in Singapore. Instead of using the G-7 summit as an opportunity to smooth over disagreements with the other members following his gratuitous and unnecessary tariff hikes, Trump seized on it to issue more threats and demands. Trump insists on seeing every international relationship as a zero-sum contest defined primarily in terms of dominance, and so he cannot imagine a productive negotiation that does not result in someone’s humiliation. Unfortunately for him, this clueless approach to diplomacy usually means that he and the U.S. are publicly humiliated again and again.

Trump’s decision to increase steel and aluminum tariffs on many of our allies and major trading partners has done a remarkable amount of damage to U.S. relations with these countries in just the last ten days. The effects of that decision aren’t going to be limited to higher prices on various goods, but will extend to strained and increasingly frayed relations with our neighbors and allies. That will have consequences for U.S. diplomacy and U.S. interests in the months and years to come that we can’t fully anticipate right now. The first of these will be the damage that has already been done to the U.S. position going into talks with North Korea.