For the past year, the United States and China have tried to manage their rivalry to reassure the world that tensions between the superpowers would not spiral into conflict. The return of President Donald J. Trump to the White House threatens to upend that delicate balance.

As a statesman, Mr. Trump’s calling card is his unpredictability. He revels in mixing threats with flattery to keep his counterparts guessing. On China, he has vowed to impose blanket tariffs on Chinese exports, and threatened duties as high as 200 percent if China were to ever “go into Taiwan,” the self-governed island claimed by Beijing.

But Mr. Trump has also praised Xi Jinping, China’s top leader, saying on a Joe Rogan podcast that he was a “brilliant guy” for controlling 1.4 billion people with an “iron fist.”

Regardless of the direction of Mr. Trump’s rhetoric, Beijing has likely concluded after Mr. Trump’s first presidency that he intends to wage a fierce rivalry with China, no matter what he says.

“Xi Jinping is an unsentimental leader with a dark interpretation of America’s intentions toward China,” said Ryan Hass, the director of the John L. Thornton China Center at the Brookings Institution. “He would be open to a friendlier leader-level relationship with Trump, but he would not expect a warmer personal relationship with Trump to dampen America’s competitive impulses toward China.”