TAIPEI (Taiwan News) — The defense ministry detected 12 Chinese military aircraft, five naval vessels, and one official ship around Taiwan between 6 a.m. on Monday and Tuesday.

Eight out of the 12 aircraft were reported to have crossed the median line of the Taiwan Strait and entered the nation’s northern and eastern air defense identification zones, or ADIZ. In response, Taiwan sent aircraft and naval ships and deployed coastal-based missile systems to monitor the Chinese activity.

In August so far, Taiwan has tracked Chinese military aircraft 53 times and ships 34 times. Since September 2020, Beijing has increased its use of “gray zone tactics” by operating military aircraft and naval vessels 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.”