When leaders of the Group of 7 countries meet in Quebec on Friday, the United States can expect a chilly reception. The other G-7 countries — France, Germany, Britain, Italy, Japan and Canada — have already expressed “unanimous concern and disappointment” with President Trump’s tariffs on steel and aluminum in a joint statement issued by their finance ministers last week.

Beijing can’t believe its luck. First, the United States abandoned the Trans-Pacific Partnership, which would have strengthened America’s ties with China’s major Asian trading partners and provided Washington with leverage to pry open China’s market. Now the tariffs on steel and aluminum — the bulk of which is imported from the European Union and Canada — benefit China by creating discord between America and its closest allies. The isolation of the United States serves to reinforce China’s narrative that the United States is an unreliable partner, and it helps advance Beijing’s goals of weakening governance mechanisms like the G-7 that don’t include China.

Once seen as the standard-bearer of free trade and defender of the rules-based order, the United States is now seen by some of its friends in Asia, too, as a unilateralist disrupter. On Sunday, at the annual security gathering known as the Shangri-La Dialogue, Defense Minister Ng Eng Hen of Singapore criticized the United States and China for undermining multilateral agreements that have benefited the whole region. “If the global commons are not preserved, or worse, fracture into de facto or formal trading and security alliances, then all of us are in for a rough time ahead,” he said.

Pointedly, Mr. Ng noted, “In a reversal of roles with the U.S., it was Chinese President Xi Jinping who champions globalization.” At the World Economic Forum last year, Mr. Xi stood up for free trade and denounced protectionist policies.