Taiwan has scrambled fighter jets as Chinese aircraft buzzed the island, including crossing the sensitive mid-line of the Taiwan Strait, in an escalation of tensions the same day a senior US official began meetings in Taipei.
Earlier on Friday, China's defence ministry announced the start of combat drills near the Taiwan Strait, denouncing what it called collusion between the Chinese-claimed island and the United States.
US Undersecretary for Economic Affairs Keith Krach arrived in Taipei on Thursday for a three-day visit. He is the second high-level US envoy to visit Taiwan in two months.
Beijing has watched with growing alarm the ever-closer relationship between Taipei and Washington, and has stepped up military exercises near the island, including two days of mass air and sea drills last week.
Taiwan's defence ministry said 18 Chinese aircraft were involved on Friday, a far larger number than Taiwan has previously announced for such encounters.
"Sep. 18, two H-6 bombers, eight J-16 fighters, four J-10 fighters and four J-11 fighters crossed the midline of the TaiwanStrait and entered Taiwan's southwest ADIZ," the ministry said on Twitter.
"ROCAF scrambled fighters, and deployed air defence missile system to monitor the activities."
The ministry showed a map of the flight paths of the Chinese jets and their crossing of the Taiwan Strait mid-line, which combat aircraft from both sides usually avoid passing through.
In Beijing, defence ministry spokesman Ren Guoqiang said Friday's drills involved the People's Liberation Army's eastern theatre command.
"They are a reasonable, necessary action aimed at the current situation in the Taiwan Strait and protecting national sovereignty and territorial integrity," Ren said.
Taiwan's presidential office urged China to exercise restraint and urged the Taiwanese not to be alarmed, saying the military had a grasp on the situation.
Government officials in Taiwan, including President Tsai Ing-wen, have expressed concern in recent weeks that an accidental military encounter could spark a wider conflict.
China on Thursday condemned Krach's visit and warned it could retaliate. It opposes any type of formal interaction between other countries and self-ruled Taiwan.
Krach's trip follows a visit in August by Health Secretary Alex Azar, the highest-level cabinet official to make the trip since the US switched formal relations from Taiwan to China in 1979.
It's among the Trump administration's moves to strengthen relations with Taiwan, which include stepped-up arms sales and supporting its participation in international forums.
Tensions between Washington and Beijing are already high as the governments spar over the coronavirus pandemic, trade, technology, Hong Kong and the South China Sea.
Australian Associated Press