The temporary reduction in tariffs that the United States and China announced in Geneva on Monday will lift, at least for now, the de facto trade embargo that had been in place between the two countries for the past month. It will reduce the chances that American shoppers will face empty shelves during the holiday season and perhaps limit the price increases they will have to endure. It sent stock prices soaring around the world.

But the deal does little to clear the cloud of uncertainty that has hung over the U.S. economy since President Trump took office in January.

If anything, the latest news serves only to reinforce the degree to which trade policy lies in the hands of one man, who sees his unpredictability as a strategic strength and scoffs at the kind of careful, deliberative process that has characterized policymaking under previous administrations.

In a little over a month, Mr. Trump has imposed steep tariffs on virtually every U.S. trading partner, then rolled them back temporarily. He has raised tariffs on China, then increased them further in response to Chinese retaliation, and now rolled back those tariffs as well — but only partially, and only for 90 days. Those back-and-forth decisions followed an earlier series of reversals, which on at least two occasions included tariffs that were announced and rescinded within a single day.

“Many of our trading partners now look at the U.S. and say, ‘Is this now the way trade policy continues in the future?’” said Steven J. Davis, a Stanford economist who has studied the way uncertainty affects the economy. “I think it’s quite clear that other countries around the world are reassessing their view of the United States as a reliable trading partner.”

A measure of economic policy uncertainty developed by Mr. Davis and two co-authors hit a record high this month, even surpassing the levels during the global financial crisis in 2008 and the coronavirus pandemic in 2020. Research has shown that such bouts of extreme uncertainty are damaging in their own right, discouraging companies from hiring and investing.