Republican Kevin McCarthy, the speaker of the US House of Representatives, met with Taiwan’s President Tsai Ing-wen in California on Wednesday, despite repeated threats of retaliation from China, AFP reported.

Pro-Beijing and pro-Taiwan protesters clashed outside the Ronald Reagan Presidential Library in Simi Valley after the arrival of the leader, who is officially “in transit” through the United States on his way home from a tour of Latin America.

The meeting deeply angered Beijing, with Chinese authorities vowing “retaliation” and fueling angry statements in recent weeks.

China considers Taiwan one of its provinces that needs to be won back, advocating “peaceful unification”, but not ruling out the use of force. According to the “One China” principle, no country should have official ties with Beijing and Taipei at the same time.

In the latest warning on Monday, the foreign minister reiterated that “China strongly opposes” a third US official meeting with Taiwan’s president.

Beijing also explained that it is ready to “firmly defend its national sovereignty and territorial integrity,” without specifically mentioning possible military maneuvers.

The United States has long maintained “strategic ambiguity” regarding the Taiwan issue. The doctrine is intended both to deter China from invading Taiwan and to prevent the island’s leaders from defying Beijing by formally declaring its independence.

Pelosi’s predecessor

Washington has recognized Beijing’s policies since 1979, but remains Taiwan’s strongest ally and main arms supplier. Support for the island is one of the few bipartisan consensuses in the US Congress, and under Tsai Ing-wen, Taiwan has moved closer to the US.

Last August, Taiwan’s president welcomed Democrat Nancy Pelosi, then the speaker of the House of Representatives, to Taiwan.

The visit angered Beijing, which has conducted military exercises around the island on a scale not seen since the mid-1990s.

The Chinese consulate in Los Angeles said in a statement Monday that McCarthy is “stubbornly trying to play the Taiwan card” to rein in Beijing. “They are likely to make the same mistake again, which will further damage Sino-US relations.”