Nine Chinese aircraft flew across the Taiwan Strait’s median line on Friday to conduct combat readiness patrols, according to Taiwan’s defense ministry, only days after China warned reprisal if President Tsai Ing-wen met US House Speaker Kevin McCarthy.

China, which claims democratically run Taiwan as its own territory despite the island’s government’s strong objections, has been enraged by what it perceives as increased US backing for Taiwan.

Tsai arrived in the United States on Wednesday, stopping off on her way to Central America.

She is expected to meet McCarthy in Los Angeles on her way back to Taipei in April, and China on Wednesday threatened unspecified retaliation if that meeting were to go ahead.

Taiwan’s defense ministry said the nine Chinese aircraft crossed at points in the north, centre and south of the strait’s median line, which used to serve as an unofficial buffer between the two sides.

Taiwan’s armed forces responded using its own aircraft and ships to monitor the situation using the principle of “not escalating conflicts or causing disputes”, the ministry said.

“The communist military’s deployment of forces deliberately created tension in the Taiwan Strait, not only undermining peace and stability, but also has a negative impact on regional security and economic development,” it said in a statement.

The ministry condemned what it called “such irrational actions”.

There was no immediate response from China.

Tsai, on her first U.S. stopover since 2019, told an event held by the Hudson Institute think tank in New York on Thursday that the blame for rising tensions lay with China, according to excerpts of her comments reported by her office.

“China deliberately raises tensions, but Taiwan always responds cautiously and calmly, so that the world can see that Taiwan is the responsible party in cross-Strait relations,” she said.

Nury Turkel, a Hudson senior fellow who attended the event, said Tsai had been clear in her desire to see the U.S. communicate to China that it would stand with the Taiwanese people if Beijing sought to destroy Taiwan’s democracy, by force or whatever means.

“Tsai was very clear in her messaging without being provocative,” Turkel said.

During her stop in New York, Tsai met with Democratic Congressman Hakeem Jeffries, according to Punchbowl News, one of many U.S. lawmakers expected to engage with her before she returns to Taipei.