Chinese leader Xi Jinping met with U.S. National Security Adviser Jake Sullivan on Thursday as the latter wound up a three-day visit with the stated aim of keeping communications open in a relationship that has become increasingly tense in recent years.

Sullivan, on his first trip to China as the main adviser to President Joe Biden on national security issues, earlier met with Chinese Foreign Minister Wang Yi and a top general from the Central Military Commission.

Starting with a trade war that dates back to 2018, China and the United States have grown at odds over a range of issues, from global security, such as China’s claims over the South China Sea, to industrial policy on electric vehicle and solar panel manufacturing. Sullivan’s trip this week is meant to keep the tensions from spiraling into conflict.

“We believe that competition with China does not have to lead to conflict or confrontation. The key is responsible management through diplomacy,” he told reporters at a news conference shortly before leaving Beijing.

Both governments are eager to keep relations on an even keel ahead of a change in the U.S. presidency in January. They said they remain committed to managing the relationship, following up on a meeting between Xi and Biden in San Francisco last November.

“While great changes have taken place in the two countries and in China-U.S. relations, China’s commitment to the goal of a stable, healthy and sustainable China-U.S. relationship remains unchanged,” Xi said.

“President Biden is committed to responsibly managing this consequential relationship to ensure that competition does not veer into conflict or confrontation, and to work together where our interests align,” Sullivan said.

The two countries agreed to work toward a phone call between Xi and Biden in the coming weeks, and Sullivan indicated the two could meet in person at the Asia-Pacific Economic Cooperation or Group of 20 summits later this year.

“The likelihood is they’ll both be there and if they are, it would only be natural for them to have the chance to sit down with one another,” he said.

Xi and Sullivan’s meeting also touched on the issues of American citizens detained in China, on Taiwan and also on the clashes between the China and Philippines in the South China Sea.

The two also discussed China’s support for Russia, as a recent U.S. assessment found that the country was exporting technology that Russia uses to manufacture missiles, tanks and other weaponry. They also discussed efforts to end the Ukraine war, but Sullivan said they did not make any progress on that issue.

Sullivan said an agreement to have a call between the military commanders in the Indo-Pacific region was a “very positive outcome” of his meetings and that they hope to deepen military-to-military communication so it can be passed on to whoever succeeds Biden as president.

The decades-old issues surrounding Taiwan have taken renewed prominence as the island’s ties with China become increasingly strained over Beijing's claims that Taiwan is part of China.

Taiwan, a self-governing island that split from communist China in 1949, has rejected Beijing’s demands that it accept unification with the mainland. The U.S. is obligated under a domestic law to provide the island with sufficient hardware and technology to deter invasion.

Danny Russel, a vice president at the Asia Society Policy Institute in New York and who served on the national security council in the Obama administration, said the meeting between Sullivan and Xi was particularly important because Sullivan was seen by the Chinese leadership as “a direct extension” of the U.S. president and that Sullivan’s messaging was viewed as “coming straight from Biden.”

Sullivan also met one of China’s vice chairs of the Central Military Commission, Gen. Zhang Youxia, on Thursday morning — a rare meeting with a visiting U.S. official.

Zhang said that reunification of Taiwan with the mainland is “the mission and responsibility” of the military, according to a statement from China’s Defense Ministry.

“China demands that the United States stop military collusion between the U.S. and Taiwan, stop arming Taiwan and stop spreading false narratives about Taiwan,” the statement said, without elaborating on what the false narratives are.

Sullivan said “it is rare that we have the opportunity to have this kind of exchange” and underscored “the need for us to responsibly manage U.S.-China relations.”

A White House statement said the two had “recognized the progress in sustained, regular military-military communications over the past 10 months” and noted an agreement announced the previous day to hold a telephone call between commanders at the theater-level in the near future. On Taiwan, the U.S. statement said only that Sullivan had raised the importance of cross-Strait peace and stability.

China suspended communication between the two militaries and in a few other fields after a senior U.S. lawmaker, then-House Speaker Nancy Pelosi, visited Taiwan in August 2022. Talks were only gradually resumed more than a year later, after Xi and Biden met outside San Francisco in November.

A theater-level call would be between Adm. Samuel Paparo, who heads the U.S. Indo-Pacific Command in Hawaii, and his Chinese counterpart, said Russel, of the Asia Society Policy Institute.

“This theater command-level dialogue is critical for crisis prevention but something the Chinese military has been resisting,” said Russel, a former assistant U.S. secretary of state for East Asian and Pacific affairs.

Paparo said this week that the U.S. military is open to consultations about escorting Philippine ships in the South China Sea, where they have clashed with Chinese ships trying to block them from small islands and outcroppings that both countries claim.