Taiwan's defense chief says that Taiwan will regard any violation of its airspace by a Chinese military aircraft as a "first strike" and launch a counterattack.

Defense Minister Chiu Kuo-cheng was responding to questions by a legislator from the ruling Democratic Progressive Party in parliament on Wednesday.

Chiu was asked if a "first strike" does not necessarily mean a missile launch, to which he answered, "Yes."

He was then asked if any Chinese military aircraft's entry into Taiwanese airspace would be seen as a first strike. Chiu replied, "Definitely."

Chiu said Taiwan will take countermeasures if it decides that the Chinese military has crossed "the red line."

Chinese military aircraft have repeatedly crossed the so-called median line in the Taiwan Strait since August. The line is an unofficial buffer to prevent unintended military clashes.

Taiwan previously defined a first strike by China's military as a missile attack or artillery shelling, saying Taiwan would not launch an attack without such moves.

But Chiu said on Wednesday China's military has undermined the tacit agreement on the median line, clearly changing the status quo.

His remark is widely seen as an attempt to warn China not to escalate the situation any further.