AP Photo/Wally Santana
A Taiwan Air Force F-16 fighter jet takes off from a closed section of highway during the annual Han Kuang military exercises
- Chinese fighters on Sunday crossed the median line, the maritime border between Taiwan and mainland China - a rare move the Taiwan's government declared a provocation.
- Taiwan scrambled fighters in response to the Chinese military's actions.
- Taiwanese President Tsai Ing-wen said she ordered the military to "forcefully expel" fighters that cross the median line at the first sign of provocation.
Taiwan has threatened to forcefully drive away Chinese military aircraft that fly too close to the island after an incursion by Chinese fighters this weekend.
Two Chinese People's Liberation Army Air Force J-11 fighter jets on Sunday crossed the "median line," a maritime border separating Taiwan from the Chinese mainland, according to Taiwan's Ministry of Foreign Affairs, which accused the Chinese military of violating a long-held agreement.
An armed Chinese J-11 fighter near a US Navy P-8A Poseidon patrol aircraft over the South China Sea in 
"It was an intentional, reckless and provocative action," the foreign ministry said in a statement. Taiwan is said to have scrambled fighter jets in response.
China routinely sends fighter jets on encirclement flights around Taiwan, but the incursion by Chinese jets Sunday was unusual. Experts told The Japan Times that it has been at least a decade since Taiwan engaged in this kind of behavior.
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When asked about the most recent incident, a China's Ministry of Foreign Affairs spokesman said he was unfamiliar with the situation.
Taiwanese President Tsai Ing-wen said in a Facebook post Monday that she has ordered the military to "forcefully expel" fighters crossing the median line at the first sign of provocation, the South China Morning Post reported Monday.
She stressed that the military stands ready to defend the rights of the people of Taiwan to choose freedom and democracy.
AP Photo/Wally Santana Taiwan air force personnel in front of a battery of Tien Chien "Sky Sword" surface-to-air missiles during an exercise in Chiayi, central Taiwan, August 24, 2018.
The latest flare-up in the closely-watched Taiwan Strait comes amid heightened tensions between Washington and Beijing over repeated US Navy sail-bys in the waterway and the impending sale of dozens of highly capable fourth-generation F-16 fighter jets to Taiwan.
China has protested US naval activities, as well as the expected sale.
There are concerns in Beijing that US activity will embolden pro-independence forces in China - something the Chinese government, which sees Taiwan as a renegade province, has refused to accept.
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"The Taiwan issue is an internal matter of China [and] concerns China's fundamental interests and the national feelings of the Chinese people, and no outside interference will be tolerated," a Chinese general told US Navy Adm. John Richardson, chief of naval operations, earlier this year. "If anyone wants to separate Taiwan from China, the Chinese army will defend the unity of the motherland at any cost."
Reunification remains a top priority for Chinese leadership, and the threat of force remains on the table, as Chinese President Xi Jinping made clear in a speech this year.
"We make no promise to abandon the use of force and retain the option of taking all necessary measures," he said in January.