President Joe Biden has opposed China's "coercive and increasingly aggressive actions" towards Taiwan, in his first meeting with President Xi Jinping.
The White House says that Biden also raised human rights concerns and Beijing's conduct in Xinjiang, Tibet, and Hong Kong.
The leaders met on the Indonesian island of Bali amid increasing tensions between the superpowers.
White House aides have repeatedly sought to play down any notion of conflict with China. But US-China relations have become increasingly strained throughout Biden’s presidency.
The pair did however agree that “a nuclear war should never be fought” and can’t be won, “and underscored their opposition to the use or threat of use of nuclear weapons in Ukraine," the White House said.
That was a reference to Russian officials’ thinly-veiled threats to use atomic weapons as its nearly nine-month invasion of Ukraine has faltered.
Biden and Xi also agreed to “empower key senior officials" on areas of potential cooperation, including tacking climate change, and maintaining global financial, health and food stability.
Xi and Biden greeted each other with a handshake at a luxury resort hotel in Indonesia, where they are attending the Group of 20 summit of large economies.
“As the leaders of our two nations, we share responsibility, in my view, to show that China and the United States can manage our differences, prevent competition from becoming anything ever near conflict, and to find ways to work together on urgent global issues that require our mutual cooperation," Biden said to open the meeting.
Xi called on Biden to “chart the right course" and “elevate the relationship” between China and the US He said he was ready for a “candid and in-depth exchange of views” with Biden.
White House aides have repeatedly sought to minimise any notion of conflict between the two nations and have emphasised that they believe the countries can work in tandem on shared challenges such as climate change and health security.
But relations have grown more strained under successive American administrations, as economic, trade, human rights and security differences have come to the fore.
As president, Biden has repeatedly taken China to task for human rights abuses against the Uyghur people and other ethnic minorities, crackdowns on democracy activists in Hong Kong, coercive trade practices, military provocations against self-ruled Taiwan and differences over Russia’s prosecution of its war against Ukraine.
Chinese officials have largely refrained from public criticism of Russia’s war, although Beijing has avoided direct support, such as supplying arms
Taiwan has emerged as one of the most contentious issues between Washington and Beijing.
Multiple times in his presidency, Biden has said the US would defend the island - which China has eyed for eventual unification - in case of a Beijing-led invasion.
Pelosi's trip prompted China, officially the People's Republic of China, to retaliate with military drills and the firing of ballistic missiles into nearby waters.
In the meeting, Biden said China's economic practices “harm American workers and families, and workers and families around the world," the White House said.
It came just weeks after the Biden administration blocked exports of advanced computer chips to China - a national security move that bolsters US competition against Beijing. Chinese officials quickly condemned the restrictions.
And though the two men have held five phone or video calls during Biden's presidency, White House officials say those encounters are no substitute for Biden being able to meet Xi in person. That task is all the more important after Xi strengthened his grip on power through the party congress, as lower-level Chinese officials have been unable or unwilling to speak for their leader.
Before the meeting, Chinese Foreign Ministry spokesperson Mao Ning had said China was committed to peaceful coexistence but would firmly defend its sovereignty, security and development interests.
“It is important that the US work together with China to properly manage differences, advance mutually beneficial cooperation, avoid misunderstanding and miscalculation, and bring China-US relations back to the right track of sound and steady development,” she said at a daily briefing in Beijing.
White House officials and their Chinese counterparts spent weeks negotiating details of the meeting, which was held at Xi’s hotel with translators providing simultaneous interpretation through headsets.
US officials were eager to see how Xi approached the Biden sit-down after consolidating his position as the unquestioned leader of the state, saying they would wait to assess whether that made him more or less likely to seek out areas of cooperation with the US.
Before meeting with Xi, Biden held talks with Indonesian President Joko Widodo, the G20 host, to announce a range of new development initiatives for the archipelago nation, including investments in climate, security, and education.
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