United States House Speaker Nancy Pelosi on Tuesday arrived in Taiwan escalating tensions with China, the Associated Press reported. She is the highest-ranking American official in 25 years to visit the country, which Beijing considers as a province that is to be unified with the Chinese mainland.

Meanwhile, ahead of Pelosi’s visit, Chinese fighter jets crossed the Taiwan Strait, AFP reported, citing Beijing’s state-owned media.

The Chinese foreign ministry said that Beijing will take “all the necessary measures to resolutely safeguard its sovereignty and territorial integrity” in response to Pelosi’s visit.

“All the consequences must be borne by the United States and the ‘Taiwan independence’ separatist forces,” the ministry said, according to Beijing’s mouthpiece Global Times.

The Chinese Army said it will conduct important military exercises and training activities, including live-fire drills, in six regions surrounding Taiwan from August 4 to August 6.

Meanwhile, Pelosi said that her delegation’s visit to Taiwan honours America’s unwavering commitment to supporting Taiwan’s democracy.

“Our discussions with Taiwan leadership reaffirm our support for our partner and promote our shared interests, including advancing a free and open Indo-Pacific region.” Pelosi said in a tweet after landing in Taipei. “America’s solidarity with the 23 million people of Taiwan is more important today than ever, as the world faces a choice between autocracy and democracy.”

Earlier today, Beijing had warned the United States saying they will have to “pay the price” if Pelosi visits Taiwan, the BBC reported.

At a press briefing in Beijing on Tuesday, foreign ministry spokesperson Hua Chunying said the US will bear the responsibility for undermining China’s sovereign security interests.

The development came a day after White House National Security Council spokesperson John Kirby said Pelosi was entitled to go where she pleased. He added that the White House respects the independence of the US Congress.

“Put simply, there is no reason for Beijing to turn a potential visit consistent with long-standing US policy into some sort of crisis or use it as a pretext to increase aggressive military activity in or around the Taiwan Strait,” Kirby said.

Pelosi is a long-time critic of China and denounced its human rights record. She is expected to meet legislators and human rights activists on Wednesday.