United States president-elect Donald Trump on Friday spoke with Taiwanese President Tsai Ing-wen on phone, marking a change in US policy and threatening the ties between Washington and Beijing. This was the first time since 1979 that the leader of the island and the US president or president-elect has communicated with each other.

Trump’s transition team said that the two leaders discussed “close economic, political and security ties”. Tsai, who happens to be Taiwan’s first female president, congratulated the billionaire business on his victory.

Taiwan and US have long severed ties after the rapprochement between Beijing and Washington. The US embassy in Taiwan was also closed down in the 1970s. Taiwan is a democratically-ruled island that Beijing believes to be a breakaway province. But since the rapprochement, Washington has followed a ‘one China’ principle. According to it, Taiwan is considered to be part of the Chinese nation.

The White House, however, said that Trump’s conversation does not signal any change in US policy. “Our fundamental interest is in peaceful and stable cross-strait relations,” White House National Security Council spokesperson Ned Price told BBC. China’s Foreign Minister Wang Yi on Saturday said the phone call was a “small trick by Taiwan” and added that Beijing’s relations with US would not be “interfered with or damaged” after this telephonic conversation, reported AP.

But experts are wary that the phone call will irk China. “This is going to make real waves in Beijing… this will put relations from day one into a very difficult place,” said Bill Bishop, who runs the Sinocism newsletter from Washington, told The Guardian. Asia director at the White House National Security Council Evan Medeiros agreed with Bishop. “Regardless if it was deliberate or accidental, this phone call will fundamentally change China’s perceptions of Trump’s strategic intentions for the negative,” The Guardian quoted Medeiros as saying.