BEIJING -- China protested on Thursday after two American jet fighters landed at an air base in Taiwan, which Beijing regards as its own territory, reportedly for the first time in 30 years.
Two US F-18 fighter jets made an emergency landing at an air force base in the southern city of Tainan on Wednesday, with US authorities saying one of the planes had developed a mechanical failure.
"We have launched solemn representations with the US," Hua Chunying, a foreign ministry spokeswoman, told a regular briefing in Beijing.
"We require the US to abide by the 'One-China Policy' and the three joint communiques between China and the US and to prudently deal with the relevant issue," she added, referring to agreements between the two that recognize Beijing as the sole government of China.
Taiwanese media described the landing as the first of its kind since the mid-1980s and speculated that it could have been a US reaction to an unprecedented People's Liberation Army Air Force exercise over the western Pacific Ocean east of Taiwan.
Several Chinese aircraft on Monday flew over the ocean for the first time via the Bashi Channel, which runs between Taiwan and the Philippines, Beijing's official Xinhua news agency said.
The US does not have formal diplomatic ties with Taiwan, officially known as the Republic of China, but has strong economic links with it and is a key military supplier.
The two planes took off from a US base in Okinawa, southern Japan, and were reportedly guided in to their landing by Taiwanese jets.
Mark Zimmer, spokesman for the American Institute in Taiwan (AIT) -- the de facto US embassy -- said one encountered a mechanical problem and an emergency landing was requested.
The crew members and aircraft were safe, he said, adding that they had been on a "routine flight" but declining to provide details.
Taiwan's defence ministry confirmed the incident.
Beijing regularly proclaims the importance of its "One China" policy, seeing Taiwan as part of its territory awaiting reunification, and often curtails the island's involvement in international agreements.
The two split in 1949 at the end of the Chinese civil war, with defeated Nationalist forces retreating to the island as Mao Zedong's victorious Communists set up the People's Republic.
China has been ramping up its military budget for years and expanding its capabilities and reach, raising concerns among its neighbours. Beijing says its actions are purely defensive.
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