TAIPEI (Taiwan News) — The defense ministry detected 27 Chinese military aircraft, 11 naval vessels, and three official ships around Taiwan between 6 a.m. on Saturday and 6 a.m. on Sunday.

Twenty-five of the aircraft were reported to have crossed the median line of the Taiwan Strait. They entered the nation’s northern, southwestern, and southeastern air defense identification zone, or ADIZ.

In response, Taiwan sent aircraft and naval ships and deployed coastal-based missile systems to monitor Chinese activity.

So far this month, Taiwan has tracked Chinese aircraft 393 times and ships 192 times. Since September 2020, China has increased its use of gray zone tactics by incrementally increasing the number of military aircraft and naval vessels operating around Taiwan.

CSIS defines gray zone tactics as “an effort or series of efforts beyond steady-state deterrence and assurance that attempts to achieve one’s security objectives without resort to direct and sizable use of force.”