He did not mention the trade war directly, and Mr. Xi has used the term “the new Long March” in speeches before to exhort officials, military officials or ordinary citizens to follow his policies. But the visit, broadcast on state-run television on Tuesday, came as tensions flare between the world’s two biggest economies. Among the officials with Mr. Xi was Liu He, his chief economic adviser and top trade negotiator.

On Wednesday, Mr. Xi told another audience in Jiangxi that the country “must be conscious of the long-term and complex nature of various unfavorable factors at home and abroad, and properly prepare for the various difficult situations.”

The trade war shows little sign of letting up. In the latest move, the Trump administration is considering placing a Chinese company called Hikvision on a list that would limit its ability to procure American technology like chips and software to meet its needs. The company, which provides equipment for China’s growing surveillance state, said in a statement on Wednesday that it “has never in the past done any business that requires us to violate human rights.”

At a daily news briefing on Wednesday, Lu Kang, a spokesman for the Chinese Foreign Ministry, said, “China opposes the U.S. practice of abusing state power and arbitrarily discrediting and suppressing foreign enterprises, including Chinese enterprises.”

In one of the first gestures hinting at a potential opening salvo, Mr. Xi on Monday visited a rare earths mine in the city of Ganzhou, which some observers saw as an attempt to remind Mr. Trump of the leverage that China has when it comes to certain resources. Rare earths are found in many of the electronics that the world uses every day, and China is the largest source. China has used its control of rare earths to exert pressure before, most notably in 2010 when it halted all exports to Japan for two months over a territorial dispute.