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

The aircraft was reported to have crossed the median line of the Taiwan Strait and entered Taiwan’s southwestern air defense identification zone, or ADIZ. In response, Taiwan sent aircraft and Navy ships and deployed coastal-based missile systems to monitor Chinese activity.

So far this month, Taiwan has tracked PLA aircraft 409 times and ships 243 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.”