U.S. President Joe Biden and his Chinese counterpart Xi Jinping vowed to reduce tensions as they attended a key summit in California on Wednesday.

The hotly anticipated meeting began with Biden greeting Xi as he stepped out of a black limousine at the scenic Filoli country estate near San Francisco before they shared a quick handshake on the front steps.

The two leaders then headed inside for painstakingly choreographed, closed-door talks on issues including Taiwan, sanctions and trade that have roiled relations between the world's largest economies.

Sitting opposite Xi at a long wooden table inside a frescoed ballroom decorated with U.S. and Chinese flags, Biden opened his remarks by saying that tensions should "not veer into conflict."

"We've known each other for a long time. We haven't always agreed, which is not a surprise to anyone, but our meetings have always been candid and straightforward and useful," he said as Xi listened through headphones.

"I think it's paramount that you and I understand each other clearly, leader to leader, but (with) no misconceptions or miscommunication. We have to ensure that competition does not veer into conflict."

Biden added that they would discuss global challenges including climate change, drugs and artificial intelligence.

Xi responded by saying "conflict and confrontation has unbearable consequences for both sides."

"For two large countries like China and United States, turning their back on each other is not an option," he said.

"Planet Earth is big enough for the two countries to succeed."

The last time Biden and Xi met in person was in Bali in November 2022, and relations nosedived after the United States shot down an alleged Chinese spy balloon in February this year.

U.S. officials have played down the chance of major breakthroughs although hoping for an agreement on restoring a hotline between the Chinese and U.S. militaries, along with cooperation on stopping supplies of the drug fentanyl.

But the main goal of the talks, which are taking place at the setting for the famed 1980s U.S. soap opera "Dynasty," is to restore predictability to the relationship, U.S. officials say.

Biden was to give a solo press conference at 4:15 p.m. (12:15 a.m. GMT Thursday) to discuss the Xi meeting, which was being held on the sidelines of the Asia-Pacific Economic Cooperation (APEC) summit in San Francisco, the White House said.

The talks, which follow months of delicate diplomatic negotiations, come against the backdrop of a long struggle for global primacy between the United States and an increasingly assertive China.

One of the most sensitive issues is Taiwan, the self-ruling democracy over which Beijing claims sovereignty and which it has not ruled out seizing by force.

Biden was expected to tell Xi that the United States will stick to its "One China" policy that emphasizes it does not support Taiwanese independence, but that it will continue to give Taiwan military aid.

"We do not want to see the tensions across the Taiwan Strait evolve into any kind of conflict," White House National Security Council spokesperson John Kirby told reporters hours before the meeting.

Biden was also expected to "raise concerns over human rights in China" including the repression of the Uyghur Muslim minority, added Kirby.

Despite lukewarm expectations, the two countries have trailed a series of possible wins from Xi's first visit to U.S. soil since he was hosted by then-President Donald Trump in 2017.

There were hopes of "progress" on cooperation to limit Chinese exports of ingredients for fentanyl, the opioid drug sweeping America. The two leaders were additionally expected to discuss the Israel-Hamas conflict and the Ukraine war.

Russia, a partner of China in what Washington sees as a growing authoritarian alliance, welcomed the San Francisco meeting, with the Kremlin calling the talks "important for everyone."

For his part, Xi was expected to push for an end to trade curbs and sanctions, with the Chinese economy struggling to shore up growth after its tough zero-COVID policy.

The Chinese leader was to host a dinner with U.S. executives after the summit.