Taiwan scrambled fighter jets Friday after accusing Chinese planes of buzzing the island during a visit by a senior State Department official.
Taiwan's defense ministry said in a tweet on Friday that 18 Chinese aircraft, including two bombers and 16 fighter planes, had crossed the sensitive mid-line of the Taiwan Strait and entered into its air defense identification zone.
This type of airspace, known as an ADIZ, is one that many countries define around their territories as a way to monitor air traffic but is not recognized by international law.
Taiwan's air force "scrambled fighters" and deployed its "air defense missile system to monitor the activities," the tweets said, showing a rough diagram of where the flights happened.
The escalation comes against a backdrop of Washington's worsening relations with Beijing, and its closer ties with Taipei and appeared to be a response to the visit to Taiwan by Keith Krach, the U.S. undersecretary for economic affairs.
The most senior State Department official the island in four decades, Krach was in Taiwan for the funeral service Taiwan's first democratically elected president, Lee Teng-hui, a man dubbed "Mr. Democracy" who died in July aged 97.
It's far from the first time such forays have been reported. Taiwan said Chinese jets entered its ADIZ for two consecutive days earlier this month while Health and Human Services Secretary Alex Azar was on a visit to Taiwan.
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China's defense ministry accused the U.S. and Taiwan of "frequently stirring up trouble," as it announced live-fire military exercises in waters between the regional rivals on Friday.
"If they intended to use Taiwan as a hostage to control China, they will be only daydreaming and doomed to perish," the ministry said in a statement, which warned that those "who play with fire will burn themselves."
China's hawkish state run tabloid, the Global Times, later suggested in an editorial that the drills were not a warning but a "rehearsal for Taiwan takeover."
Beijing views Taiwan as an illegitimate breakaway province, “a sacred and inalienable part of China’s territory,” as the Defense Ministry put it Friday. When the civil war in China between the communists and nationalists ended in 1949 with the former triumphant, the latter set up a rival government in Taipei.
Since the 1970s the U.S. has officially only recognized Beijing, but has since become Taiwan's main arms supplier and international backer.
While tensions have risen between China and the administration of President Donald Trump, the White House is planning to sell a large weapons package to Taiwan, including mines, cruise missiles and drones, multiple anonymous sources with knowledge of the deals told Reuters Friday.
In the past, the U.S. has spaced out and limited such sales as to minimize backlash from Beijing.
Speaking to reporters after a meeting with Guyana's President Irfaan Ali, Secretary of State Mike Pompeo, said: "We sent a delegation to a funeral. And the Chinese have apparently responded by military blustering."
Reuters contributed to this report.