Having cast aside presidential term limits, China is bracing for relations with the United States to enter a dangerous period under the continuing leadership of President Xi Jinping, intending to stand firm against President Trump and against policies it sees as attempts to contain its rise, according to Chinese analysts.

As Xi Jinping

Even before the announcement on Sunday that he could rule for the foreseeable future, Mr. Xi had ordered the Chinese military to counter the Pentagon with its own modernization in air, sea, space and cyber weapons, the analysts said, partly in response to Mr. Trump’s plans to revitalize American nuclear forces.

Rather than beginning a final term next month as a lame duck, Mr. Xi will govern with new authority to pursue his agenda of making China a global power even if it risks putting Beijing in conflict with Washington and triggering a new Cold War after 40 years of mutual engagement, the analysts said.

Asked if conflict was likely in the region, Mr. Cui said: “I don’t exclude that possibility. In this transitional period, it depends on how the two sides handle it.”

He added that it was “not normal for China to be under U.S. dominance forever. You can’t justify dominance forever.”

Mr. Xi appears to share the view of many Chinese analysts and military officials that the United States is a superpower in decline — and that China must step into the vacuum it leaves behind.

He has accelerated the military’s plans to build a blue-water navy, increased spending on weaponry in outer space, and established China’s first military bases abroad. He has promoted a global infrastructure program to extend Beijing’s influence and ignored Western concerns about human rights, which have diminished under the Trump administration.

“Our country must not be disturbed by the outside world or lose our confidence as the West grows increasingly vigilant toward China,” it said.

In some respects, Mr. Xi’s move to extend his rule in tandem with his drive to make China a dominant global power should not have surprised the United States, Chinese analysts said.

“Xi is exploiting the space that America voluntarily abandoned,” said Shi Yinhong, a professor of international relations at Renmin University. In contrast, he said, “China speaks again and again of globalization as a good thing.”

Their views mirror those of American strategists who also see these fields as critical to success in modern war, he said.

But Chinese analysts said that Beijing did not believe the effort would amount to much because the United States was unwilling to spend money on the projects.

“In the short term,” Mr. Shi said, “China does not care about it because the ability to form a real coalition is limited.”