“On economic issues, China has more and more leverage,” said Wu Xinbo, the director of the Center for American Studies at Fudan University. “If we feel he is still pushing the Taiwan issue, we will take action. If he wants to keep it up on Taiwan, it will only backfire.”

American trade officials worry that China could intensify its discrimination against American technology firms by using the country’s antimonopoly laws. Last year, the Chinese government slapped a $975 million fine on Qualcomm, a San Diego-based chip maker, for what it said were licensing infractions.

A few years ago, there were worries that China might suddenly dump a large portion of its holdings of Treasuries, pushing up interest rates in the United States. Those fears ebbed as China pared its holdings gradually. Its holdings of Treasuries peaked at $1.65 trillion in March 2014, declining to about $1.3 trillion, said Brad Setser at the Council on Foreign Relations.

Experts say that even if the country sold more, it may not have much effect because interest rates are already low, global demand for Treasuries has been strong, and the Federal Reserve could buy more bonds if needed to offset action by China.

China could also weaken its currency, something Mr. Trump has argued it already does to make its products cheaper. But that could also result in more Chinese taking their money out of the country, as well as inflation for a nation that increasingly buys what it needs from abroad, like oil, because a weak currency means China must pay more for imported goods.

Finally, China could order its state-owned companies and private enterprises to slow their investments in the United States. A recent study by the Rhodium Group, a New York-based economic policy outfit, showed that since 2015, the amount of Chinese direct investment in the United States has outweighed the amount of American investment in China.

North Korea

Mr. Trump said on Sunday, “And frankly, they’re not helping us at all with North Korea.”

China has in fact cooperated with some American initiatives on curbing North Korea’s nuclear program, specifically backing United Nations economic sanctions last month aimed at checking the North’s foreign exchange earnings from coal, its biggest export earner.