Donald Trump has been branded "as ignorant as a child" by a Chinese newspaper.
The Global Times, a state-run paper, made the comment in a scathing analysis of the President-elect's approach towards Taiwan and the one-China policy.
Trump said in an interview he did not feel "bound" by the policy - which prevents official relations with Taiwan - unless China and the US strike another trade deal.
But the billionaire's comments on Fox News grated on some Chinese officials, many who were already angered by a public phone call between Trump and the Taiwanese president.
China considers the self-governing island part of its territory, and any mention of a separate state is a grave insult.
One-China has long been part of US policy.
In Trump's interview, he said he would not feel "bound by a one-China policy unless we make a deal with China having to do with other things, including trade".
His comments came just a week after a public phone call with Taiwan President Tsai Ing-wen - the first such call by an American leader in four decades.
Hours after the interview, the Global Times wrote: "Trump, please listen clearly: 'One China' cannot be traded.
"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".
The paper added: "Many people might be surprised at how the new US leader is truly a 'businessman' through-and-through'.
"But in the field of diplomacy, he is as ignorant as a child".
The Global Times, published by the Communist Party's mouthpiece, the People's Daily, often runs commentaries that target nationalistic sentiment with provocative language.