China summoned Washington's ambassador to Beijing and warned of serious consequences after House Speaker Nancy Pelosi visited Taiwan on Tuesday.
China's foreign ministry, early on Wednesday local time (Tuesday night GMT), lodged a protest with U.S. Ambassador Nicholas Burns over the unannounced visit by Pelosi to Taiwan, which Beijing calls its "breakaway province."
"The nature of Pelosi's visit is extremely vicious and the consequence is very grave," China's Vice Foreign Minister Xie Feng told Burns.
"The U.S. must pay the price for its own mistake. China will take necessary and resolute countermeasures and we mean what we say," the Chinese diplomat told the U.S. ambassador.
Calling Pelosi's trip an "unscrupulous move," Xie told Burns that the U.S. should have "prevented her (Pelosi) from going against the historical trend but instead indulged her and colluded with her, which exacerbates the tension in the Taiwan Straits and seriously damages China-U.S. ties."
"The Chinese side will not sit idly by," Xie told Burns, saying the visit is "a serious provocation and violation of the one-China principle," Chinese daily Global Times reported.
Despite a string of warnings, including military action, Pelosi flew to Taiwan from Malaysia on Tuesday.
Pelosi was received by Taiwanese Foreign Minister Joseph Wu as she landed at the Taipei Songshan Airport at around 10:44 p.m. local time (2:44 p.m. GMT). Two hotels have been booked to host the accompanying delegation of U.S. lawmakers and officials.
This came as Beijing ratcheted up its messages urging the senior U.S. deputy to abandon her trip, which was not on the official agenda of Pelosi's four-nation Asia tour.
Pelosi, the first speaker of the U.S. House of Representatives to visit Taiwan in 25 years, will meet Taiwanese President Tsai Ing-wen and also engage with Taiwanese lawmakers.
In 1997, Republican Newt Gingrich was the last House speaker to visit the self-ruled island, which has insisted on its independence since 1949.
Soon after Pelosi landed in Taiwan, the Chinese military announced to hold military drills around the self-ruled island, home to over 24 million people.
The Taiwanese defense ministry said around 21 Chinese military aircraft entered its air defense identification zone – a buffer zone outside a country's airspace, where it has the right to ask incoming aircraft to identify themselves.
Chinese state media released videos showing that the People's Liberation Army (PLA) commenced joint military exercises "surrounding the island of Taiwan."
The drills featured J-20 stealth fighter jets and test firing of conventional missiles that analysts said could fly over the island.