A phone call between U.S. President-elect Donald Trump and Taiwan President Tsai Ing-wen (蔡英文) is grabbing headlines around the world.

The call, which took place on Friday, is thought to be the first time a president or president-elect of the United States has directly contacted the leader of Taiwan since 1979, when formal diplomatic ties between the United States and China were established.

A Trump spokesman said the president-elect was "well aware of what U.S. policy has been" on Taiwan, according to reports.

After the call, Trump took to Twitter to clarify how the call came about saying:

"The President of Taiwan CALLED ME today to wish me congratulations on winning the Presidency. Thank you!" [sic]

An hour later he was back on Twitter, in an apparent response to further questions about the call.

"Interesting how the U.S. sells Taiwan billions of dollars of military equipment but I should not accept a congratulatory call."

“During the discussion, they noted the close economic, political and security ties [that exist] between Taiwan and the U.S.,” the Trump transition team said, Wall Street Journal reports. “President-elect Trump also congratulated President Tsai on becoming president of Taiwan earlier this year.”

The call marks a major break with convention, as China has for decades blocked formal diplomatic relations between the U.S. and Taiwan.

At the time of writing, Beijing had not commented on the phone call. However, commentators believe the event is likely to “infuriate” China’s leadership.

After Trump won the U.S. presidential election in November, Tsai congratulated the president-elect and said the U.S. is the most important democratic country in the world and also Taiwan's most "solid" international partner. She looked forward to working with Trump and his government in improving U.S.-Taiwan relations and becoming a cornerstone in maintaining peace and stability in the Asia-Pacific region.

At that time, Christian M. Marchant, political section chief at the American Institute in Taiwan (AIT), said U.S.-Taiwan relations will not see any drastic changes with either U.S. presidential candidate elected.

In April, the U.S. House Committee of Foreign Affairs passed the resolution “reaffirming the Taiwan Relations Act and the Six Assurances as the cornerstone of United States-Taiwan relations."

The Assurances include promises of military sales and the role of the U.S. in cross-Strait relations, stating “[The US] would not exert pressure on the Republic of China [Taiwan] to enter into negotiations with the PRC [China]."

Editor: Olivia Yang