China has issued a pointed warning over Taiwan just hours after Joe Biden and Xi Jingping held a landmark meeting.
A statement released by Beijing on Monday described attempts to block their aims of "national reunification" with the self-ruled island as a "red line that must not be crossed" in future relations with the United States.
The Asian superpower continues to claim US-allied Taiwan as part of its territory under its 'One China' policy, despite the wishes of the majority of its people to remain independent of the mainland.
The comments come after Joe Biden told reporters that he and the Chinese premier had been "straight forward and willing to compromise" on a number of issues following their three-and-a-half hour discussion in Bali, Indonesia ahead of a crucial G20 summit.
The US president said in the aftermath there would be "no new Cold War" with China, while the White House said he had raised the country's "coercive and increasingly aggressive actions" towards Taiwan and general human rights abuses in the meeting.
But a Chinese readout of the same meeting showed no change in their position on the island, stating: "President Xi gave a full account of the origin of the Taiwan question and China's principled position."
"He stressed that 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.
"Resolving the Taiwan question is a matter for the Chinese and China's internal affair[s]. It is the common aspiration of the Chinese people and nation to realize national reunification and safeguard territorial integrity."
The Chinese statement added that they hoped the "U.S. side will match its words with action", claiming Joe Biden had previously signalled the United States' opposition to "Taiwan independence".
China's One China policy means diplomatic relations with other nations can be cut if they formally recognise Taiwan as an independent state.
The US, meanwhile, has deviated from its previous policy of "strategic ambiguity" in response to an invasion of the island by China and insisted it would be forced to step in if China attacked Taiwan.