The Chinese government has said it is "seriously concerned" about Donald Trump's threat to change the US's stance on the recognition of Taiwan as an independent state.
The President-elect has suggested he could withdraw American support for the so-called "One China" principle unless Beijing makes concessions on other issues like trade.
The principle dictates that self-governing Taiwan is a part of China, and demands any ally of Beijing to have no official relations with Taipei.
Geng Shuang, a spokesman for the Chinese foreign ministry, warned that if the "One China" principle is "compromised or disrupted, the sound and steady growth of China-US relations as well as bilateral cooperation in major fields would be out of the question".
It comes after a TV interview on Sunday in which Mr Trump said 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 status of Taiwan is the most sensitive issue in US-China relations, and Mr Trump sparked the diplomatic row when he accept an official phone call from the Taiwanese President Tsai Ing-wen. It was the first time an American president or president-elect has publicly spoken to a Taiwanese leader in nearly four decades.
Some reports have questioned whether Mr Trump was aware of the significance of the call, and he has admitted he was informed only "an hour or two before".
But on Sunday, Mr Trump defended the decision. "Why should some other nation be able to say I can't take a call?" he said. "I think it actually would've been very disrespectful, to be honest with you, not taking it."
Earlier on Monday, an official Chinese newspaper called Mr Trump "as ignorant as a child" over his stance on Taiwan.
Hours after Mr Trump's interview with Fox News aired, the Global Times published a Chinese-language editorial headlined: "Trump, please listen clearly: 'One China' cannot be traded."
It read: "China needs to launch a resolute struggle with him. Only after he's hit some obstacles and truly understands that China and the rest of the world are not to be bullied will he gain some perception.
"Many people might be surprised at how the new US leader is truly a 'businessman' through-and-through," the paper said, referring to Mr Trump's suggestion of using the "One China" policy as a bargaining chip. "But in the field of diplomacy, he is as ignorant as a child."
