U.S. President Joe Biden warned President Xi Jinping on Monday that the United States would enhance its security position in Asia if Beijing cannot rein in North Korea's weapons programmes, and during a three-hour meeting the two leaders also had strong words about Taiwan.

Joe Biden meets with Xi Jinping

Biden told a news conference after his first in-person talks with Xi since becoming president in early 2021 that they had blunt talks over a wide array of issues that are contributing to the worst U.S.-Chinese ties in decades.

But he said there was no need for a new Cold War, and added he did not think China was planning a hot one.

In a statement after their meeting, Xi called Taiwan the "first red line" that must not be crossed in U.S.-China relations, Chinese state media said.

Biden said he sought to assure Xi that U.S. policy on Taiwan has not changed, seeking to lower tensions over the self-ruled island. "I do not think there's any imminent attempt on the part of China to invade Taiwan," he told reporters.

On North Korea, Biden said if China is unable to rein in Pyongyang's weapons programmes, the United States would do more to further protect U.S. allies in the region.

Beijing had halted a series of formal dialogue channels with Washington, including on climate change and military-to-military talks, after U.S. House of Representatives Speaker Nancy Pelosi visited Taiwan in August.

"The Taiwan question is at the very core of China's core interests, the bedrock of the political foundation of China-U.S. relations, and the first red line that must not be crossed in China-U.S. relations," Xi was quoted as saying by Xinhua news agency.

Beijing views Taiwan as an inalienable part of China. The island's democratically-elected government rejects Beijing's claims of sovereignty over it. Beijing has frequently accused the United States in recent years of encouraging Taiwan independence.

The two sides had set up a mechanism for more frequent communications and U.S. Secretary of State Antony Blinken will travel to China to follow-up on discussions, Biden said. "I think we understand each other," he said.