On Sunday, President-elect Donald Trump told Fox News that he wouldn't feel "bound by a one-China policy unless we make a deal with China having to do with other things, including trade."
The one-China policy has guided U.S.-China discourse since 1979, when Washington established diplomatic relations with Beijing and downgraded its embassy in Taiwan.
The Chinese government has responded to Trump's comments by expressing "serious concerns."
A spokesman for China's foreign ministry said that any damage to the "political foundation" of the U.S.-China diplomatic relationship could make further cooperation between the two countries "out of the question," The Associated Press reports.
Trump's comments came more than a week after he spoke with Taiwanese President Tsai Ing-Wen on the phone, a startling departure from long-standing diplomatic policy. Leaders of the U.S. and Taiwan haven't communicated directly in decades.
"The United States and China have agreed on the one-China policy – a diplomatic recognition of Taiwan as part of one China — for four decades," NPR's Rob Schmitz reports from Shanghai.
"Chinese state media were quick to respond to Trump's comments," Rob says. "The Global Times printed an op-ed stating the one-China policy is not for sale, going on to say that Trump is playing a dangerous game in which he's treating Taiwan as a pawn."
Global Times, which is controlled by the Communist Party, also called Trump "as ignorant as a child" when it comes to diplomacy, language far stronger than that used by Chinese officials, the AP reports.
"On Thursday, less than a week after Trump's conversation with Taiwan's president, China's military flew a nuclear-capable bomber over disputed islands in the South China Sea," Rob notes.
Robert Daly, director of the Woodrow Wilson Center's Kissinger Institute on China and the United States, spoke to NPR's Morning Edition after Trump's controversial phone call with Taiwan's president.
"Taiwan is China's core interest," Daly said. "And it defines a core interest as something it is willing to go to war over."