TAIPEI (Taiwan News) — The Ministry of National Defense said it had tracked 15 aircraft and four ships from China’s military around the country by 5 p.m. Wednesday (Oct. 12).

Of the 15 People’s Liberation Army Air Force (PLAAF) aircraft, six, including one drone, entered the southwest corner of Taiwan’s air defense identification zone (ADIZ), the military tweeted. The six included three Shenyang J-16 jets, a BZK-007 reconnaissance drone, a Shaanxi Y-8 anti-submarine warfare aircraft, and a Shaanxi Y-8 reconnaissance plane.

As is common in such situations, Taiwan’s military tasked combat air patrol aircraft and naval vessels, deployed land-based air defense missile systems to monitor and respond to the Chinese activities, and issued radio warnings.

The PLAAF has been sending its aircraft into Taiwan’s ADIZ increasingly for the past few years, with a sharp increase as well as crossings over the median line of the Taiwan Strait noted after United States House Speaker Nancy Pelosi’s visit to Taipei in early August.

On Tuesday (Oct. 11), the ministry said it was updating its definition of “first strike” to include the intrusion by military drones into Taiwan’s airspace, meaning the area up to 12 nautical miles from its coastline. The earlier definition only covered manned military aircraft.