In response to the 27 Chinese war planes that have entered Taiwan’s air defense zone, the self-ruled island dispatched fighter jets and deployed missile systems to fend off Beijing’s actions.

China reportedly sent 16 Chinese Su-30 fighters and 11 other jets into the zone—with 22 of the aircraft crossing the median line separating China and Taiwan—the island’s defense ministry told Reuters on Wednesday.

The latest mission from the People’s Liberation Army (PLA) was among a series of moves China has made after House Speaker Nancy Pelosi touched down in Taiwan amid warnings from Beijing. Her visit, which received bipartisan support on Capitol Hill, was the first from a high-level U.S. official in 25 years.

China also summoned U.S. Ambassador Nicholas Burns to Beijing and halted some food trade with Taiwan in retaliation for Pelosi’s stop on the island.

China had already cautioned Pelosi with war planes before she arrived in Taipei on Tuesday.

On Monday night, Chinese Ambassador to the United States Qin Gang shared a video showcasing the PLA on Twitter, writing, “This is the People’s Liberation Army, the guardian of the Chinese people for 95 years, who will not sit idly by when it comes to safeguarding national sovereignty and territorial integrity.”

Chinese military exercises are expected to take place within Taiwan’s defense territory this week, an unprecedented move that a senior Taiwanese official told Reuters would amount to “a sea and air blockade of Taiwan.”

Pelosi, a staunch defender of Taiwan, defended her trip on Tuesday, saying she traveled to the island “to make unequivocally clear that we will not abandon our commitment to Taiwan.”

Taiwan’s independence has long been controversial. While Taiwan is self-governed, China has held that the province will eventually join the nation under its One China Policy.

“The Taiwan question is the most important and most sensitive issue at the very heart of China-U.S. relations,” China’s foreign ministry said in a Tuesday statement. “The Taiwan Strait is facing a new round of tensions and severe challenges, and the fundamental cause is the repeated moves by the Taiwan authorities and the United States to change the status quo.”

Beijing has argued that President Joe Biden should have prevented the House speaker’s trip, but the White House has reaffirmed that the president does not have authority over the travels of members of Congress.

White House National Security Council Strategic Communications Coordinator John Kirby told reporters that Pelosi’s visit is “perfectly consistent with American policy” and that the U.S. doesn’t want it to “spiral into any kind of a crisis or conflict.”