President Donald Trump at a G-7 working session on Sunday. Photo: Jeff J. Mitchell/Pool /Getty Images

The annual summits of the Group of Seven industrialized democracies — the gathering that for decades was able to shape the trajectory of the global economy and determine which issues should sit atop a notional shared agenda — seem to particularly unnerve President Trump.

Is it because it’s one of few times he has to face elected leaders who are more popular and more legitimate than he is? Or that the Europeans represent the kinds of elites that his father disdained? Or because the G-7 nations, for all their flaws, represent a source of economic and political power he has been unable to suborn or corrupt — and, as he faces economic weakness at home for the first time, could be aligned against him?

The 2017 G-7, in retrospect, probably told us all we needed to know when world leaders took a walk in Sicily and Trump followed along in a golf cart. At the 2018 meeting, Trump lost control in a session and threw Starburst candies at Angela Merkel, then un-endorsed the agreed-upon summit document, and hate-tweeted at Canadian Prime Minister Justin Trudeau while flying away.

So far at this year’s G-7, held in the seaside resort town of Biarritz in France, the sheer volume of Trump’s reversals are getting the most global attention. On Saturday, he sat down to lunch with French President Emmanuel Macron, bragging about their friendship, while his team fanned out to complain that Macron had filled the meeting agenda with what they see as “niche” issues like gender, inequality, and global warming. He seemed, to his hosts, to have agreed that France could represent the group in outreach to Iran … until he hadn’t. He said in public that he did have second thoughts about his aggressive use of tariffs against China; a few hours later, his press office explained that what he meant was that he wished he’d imposed even higher tariffs.

No, Trump isn’t doing this because he’s senile or mentally ill. It’s a strategy he has adopted throughout his presidency, using international meetings as backdrops to send a message home to his core supporters: Look at me being tough, putting America first and showing disdain to all those fancy foreigners who disdain you, cheated you, and took your jobs away.

To be fair, Trump is hardly the only world leader who uses these meetings for domestic grandstanding. Macron pulled quite a stunt on Sunday when the foreign minister of Iran, at Macron’s invitation, arrived at the summit venue unannounced. (Some furious Trump administration officials said they were blindsided by the move, while another claimed the president “is never surprised by these types of actions.”)

At the beginning of Trump’s presidency, our partners and allies told themselves (as lots of senior Republicans and Democrats from the foreign-policy establishment told them) not to worry about the president’s public pronouncements because, somewhere, adults were in control. As the “adults” failed or were forced from their jobs, world leaders shifted strategies. Macron and Japanese Prime Minister Shinzo Abe in particular have sought to flatter, befriend, and wrangle Trump — a strategy that was still in evidence this weekend, as were its limits.

The president repaid Macron’s luncheon invitation by blowing up the dinner discussion on the behalf of Russian President Vladimir Putin and forcing Macron, as the Associated Press put it, to “play down his role and acknowledge Trump’s status as ‘the president of the world’s number one power.’” Abe held a press conference to announce the outlines of a trade deal with the U.S., but had to stand by while Trump brushed off the latest North Korean missile tests, and then gently correct the president that Japanese businesses, not the government, would be purchasing corn from the U.S.

Macron has already given up on the idea of the summit ending in a shared statement, but this year, ironically, it may be Trump who wants shared action the most. With recession fears and an election year looming, the Trump team would like some good old-fashioned 1980s-style economic coordination among the industrial democracies to spur commerce among themselves, sustain markets, and drive up U.S. exports.

The problem? Our partners’ economies are hurting worse than ours — thanks to the costs and unpredictability of Trump’s trade war. All would like a better deal with China, but they would settle for a steady, predictable deal that lets their economies keep trading and growing. They know they cannot order their corporations out of China, even if Trump does not. And they don’t know whether Trump will do a deal with Beijing and undercut them next week.

As Intelligencer’s Josh Barro writes, the president’s economic policies are no longer self-limiting. The damage he has wrought has outgrown the ability of American markets to contain it. His global security policies, on the other hand, were designed to break existing institutions and then charge our allies to clean up the mess. But by breaking down trust on the security side, Trump has peeled away one of the big reasons for Europe and Japan to offer us give on the economic side.

No wonder Trump and his team are frantically self-contradicting at every turn. Heather Conley, a former Bush Administration official who studies Europe at the Center for Strategic and International Studies, called this moment “the institutionalization of America alone.” And even at the beach in France, alone is not where you want to be when winter is on the way.