President Donald Trump touted relations with China as "extremely strong" following a call with Chinese leader Xi Jinping, who told Trump that Taiwan's "return to China" is a key part of Beijing's vision for the world order.
The call, not previously flagged by either country, came weeks after the two leaders met in South Korea, where they agreed to a framework for a trade deal that has yet to be finalised.
China is locked in its biggest diplomatic crisis for years with US ally Japan. This month, Japanese Prime Minister Sanae Takaichi said any Chinese attack on democratically governed Taiwan could trigger a Japanese military response.
"China and the United States once fought side by side against fascism and militarism, and should now work together to safeguard the outcomes of World War Two," Xi was quoted as saying by China's official Xinhua news agency, adding that "Taiwan's return to China is an integral part of the post-war international order."
China regards Taiwan as part of its territory and has not ruled out the use of force to take control of it. The island's government rejects Beijing's claim and says only Taiwan's people can decide their future.
Taiwan's Premier says for Taiwan's 23 million people a 'return' to China is not an option.
He says the Republic of China (Taiwan) is a fully sovereign and independent country.
Trump made no mention of Taiwan in a Truth Social post on his "very good" call with Xi, which he said covered many topics, including Ukraine, fentanyl, and US farm products.
"Our relationship with China is extremely strong! This call was a follow up to our highly successful meeting in South Korea, three weeks ago. Since then, there has been significant progress on both sides in keeping our agreements current and accurate," Trump said.
He said he accepted Xi's invitation to visit Beijing in April, and had invited Xi for a state visit to the US later in the year.
White House Press Secretary Karoline Leavitt told reporters the call with Xi was focused on trade and lasted about an hour.
