Donald Trump risked sparking a major diplomatic dispute with China on Friday after speaking on the phone on with Taiwan’s President Tsai Ying-wen — the first time a US president has spoken with a Taiwanese counterpart since 1979.

The two countries have not had diplomatic relations since that year, so the president-elect broke with 37 years of US policy.

It was unclear whether Team Trump was signaling a broad change in US policy or if the call was an unintentional blunder.

China’s foreign minister responded by saying he hopes Beijing-Washington relations won’t be “interfered with or damaged.”

The minister, Wang Yi, also dismissed the phone call as “just a small trick by Taiwan.”

“The one-China policy is the cornerstone of the healthy development of China-US relations and we hope this political foundation will not be interfered with or damaged,” Wang said.

The US adhered to the so-called “One China” policy since 1972 after President Nixon traveled to China for talks with Chairman Mao.

In 1978, President Jimmy Carter recognized Beijing as China’s only legitimate government, and the US embassy in Taipei closed a year later.

Trump’s transition team did not immediately respond to a request for comment.

“The Chinese leadership will see this as a highly provocative action, of historic proportions,” Evan Medeiros, former Asia director at the White House national security council, told the Financial Times.

“Regardless if it was deliberate or accidental, this phone call will fundamentally change China’s perceptions of Trump’s strategic intentions for the negative. With this kind of move, Trump is setting a foundation of enduring mistrust and strategic competition for US-China relations.”

Trump issued a press release mentioning the call, one of four he had Friday with world leaders, including of the nations of Afghanistan, Philippines and Singapore.

“President-elect Trump spoke with President Tsai Ing-wen of Taiwan, who offered her congratulations. During the discussion, they noted the close economic, political, and security ties exists between Taiwan and the United States. President-elect Trump also congratulated President Tsai on becoming President of Taiwan earlier this year,” the release said.

On the campaign trail, Trump accused China of stealing US jobs and manipulating currency.

The call comes just days after Trump raised eyebrows by calling Pakistani Prime Minister Nawaz Sharif and telling him “you are a terrific guy. You are doing amazing work which is visible in every way. I am looking forward to see you soon. As I am talking to you, Prime Minister, I feel I am talking to a person I have known for long.”

The call alarmed India’s leaders, who have a fraught relationship with their South Asian neighbor.