The Speaker of the United States House of Representatives, Nancy Pelosi, has arrived in Taiwan, despite China’s threats that Washington will face “serious consequences”.

She was received at Taipei airport by Taiwan’s foreign minister, Joseph Wu.

“The visit to Taiwan by our congressional delegation honors America’s unwavering commitment to supporting Taiwan’s vibrant democracy,” Pelosi said.

“America’s solidarity with Taiwan’s 23 million people is more important than ever as the world faces the choice between autocracy and democracy,” she added.

The senior American official is expected to meet with the president of Taiwan, Tsai Ing-wen, as well as to visit the Parliament of this country on Wednesday. She is expected to end the visit on the afternoon of August 3.

Her visit to Taiwan comes as Chinese state media reported on Tuesday that Chinese warplanes are flying over the Taiwan Strait.

“Chinese Su-35 jets are passing over the Taiwan Strait,” state media TV CGTN reported, without providing further details.

Pelosi’s visit to Taipei, Taiwan, comes amid intensified warnings from China and four US warships, including an aircraft carrier, were positioned in waters east of the island.

The USS Ronald Reagan, which had been transiting the South China Sea, is currently in the Philippine Sea, east of Taiwan and the Philippines and south of Japan, a US Navy official confirmed to Reuters on Tuesday.

Ronald Reagan (CVN 76) is the ninth Nimitz-class nuclear-powered aircraft carrier and is named in honor of the 40th president of the United States.

“Until they are able to respond to any eventuality, these are normal routine displacements,” said the official, who spoke on condition of anonymity.

The US Navy official said the USS Tripoli attack ship was also in the area as part of a deployment to the region that began in early May from its home port of San Diego.

The confirmation of the deployments came as signs of military activity emerged on both sides of the Taiwan Strait ahead of Pelosi’s visit.

Pelosi, a longtime critic of China, visits Taiwan after the United States said it would not fear a Chinese “threat of military force” during the visit.

In addition to Chinese planes flying close to the dividing line on Tuesday morning, several Chinese warships remained near the line as of Monday, a source familiar with the matter told Reuters.

The source said Chinese warships and aircraft “narrowed” the dividing line on Tuesday morning, an unusual move the source described as “very provocative”.

The source said the Chinese aircraft repeatedly made tactical maneuvers to briefly “touch” the dividing line and circle back to the other side of the Strait on Tuesday morning, while Taiwanese jets were on standby nearby.

China’s Ministry of Defense and Ministry of Foreign Affairs did not respond to requests for comment on these developments.

China said earlier on Tuesday that the United States would “pay the price” if Pelosi visits Taiwan during her trip to Asia.

“The US side will bear responsibility and pay the price for undermining China’s sovereign security interests,” Foreign Ministry spokeswoman Hua Chunying said at a regular media briefing in Beijing.

China considers Taiwan its territory and has indicated through repeated warnings that it would consider Pelosi’s visit a major provocation.

Neither side’s planes normally cross the dividing line between Taiwan and China.

Taiwan’s Defense Ministry said on Tuesday it is in full control of military activities near Taiwan and will deploy forces proportionately in response to “enemy threats” as tensions with China rise.

The ministry had “reinforced” its level of combat readiness from Tuesday morning to midday Thursday, Taiwan’s Central News Agency reported, citing unnamed sources.

In the southeastern Chinese city of Xiamen, which lies opposite Taiwan and is a major military base, residents reported seeing armored vehicles in motion and posted pictures online. The photos have not yet been verified by Reuters.

Chinese social media was dominated by fear, both of potential conflict and patriotic fervor over the prospect of reunification with Taiwan.

Since last week, the People’s Liberation Army has conducted various exercises, including live-fire exercises, in the South China Sea, Yellow Sea and Bohan.

Some regional military analysts say increasing deployments in times of tension increases the risk of accidents, even if neither side wants an actual conflict.