China has warned that a change in the United States’ adherence to the “One China” policy and in favor of the official recognition of Taiwan will harm bilateral ties between Beijing and Washington and “seriously” damage peace and stability across the Taiwan Strait.

“Upholding the ‘One China’ principle is the political basis of developing China-US relations, and is the cornerstone of peace and stability in the Taiwan Strait,” said spokesman for Beijing’s Taiwan Affairs Office An Fengshan on Wednesday.

“If this basis is interfered with or damaged, then the healthy, stable development of China-US relations is out of the question, and peace and stability in the Taiwan Strait will be seriously impacted,” he said.

The remarks came following recent remarks by US President-elect Donald that he did not feel “bound by a ‘One China’ policy” unless Washington could get concessions from China in trade and other areas.

The billionaire businessman had earlier angered China by speaking directly with Taiwanese President Tsai Ing-wen in a phone call, a major break from US diplomatic protocol since 1979.

Under the “One China” policy adopted by the US that year, Washington has been recognizing Chinese sovereignty over Taiwan and maintaining only unofficial ties with Taiwan, which broke from the Chinese mainland in 1949.

China’s Foreign Minister Wang Yi warned Trump on Monday that anyone who challenged Beijing’s interests on the island will “lift a rock only to crush his own toes.”

China also gave Taiwan a stern warning that declaring independence would be a “dead end.”

Spokesman An also said in his Wednesday remarks that Beijing’s stance of opposing and blocking “Taiwan independence splittism” remains “firm and unmovable.”

“We have unshakable willpower, ample confidence, and sufficient capability,” he added. “Facts will show those people that ‘Taiwan independence’ is a dead end.”

‘You don’t talk to a partner like that’

Meanwhile, French Foreign Minister Jean-Marc-Ayrault has criticized the American president-elect’s rhetoric on China, which he called a “partner.”

“China is a big country. We can have our differences with China, but you don’t talk to a partner like that,” Ayrault said in an interview with the local France 2 television on Wednesday for showing a lack of respect for Beijing by questioning the ‘one China’ principle.

“We need to avoid things spiraling out of control,” the French foreign minister added.

“So I hope that the new team will have learnt enough so that we manage an uncertain world with more sang-froid and responsibility,” he said in an apparent reference to Trump’s incoming team.