TAIPEI (Taiwan News) — The defense ministry detected eight PLA aircraft, seven naval vessels, and one official ship around Taiwan between 6 a.m. on Saturday and Sunday.

Six of the eight aircraft were reported to have crossed the median line of the Taiwan Strait and entered the nation’s northern, southwestern, and eastern air defense identification zone, or ADIZ. In response, Taiwan sent aircraft and naval ships and deployed coastal-based missile systems to monitor Chinese activity.

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.”