TAIPEI (Taiwan News) — The Ministry of National Defense tracked nine Chinese naval vessels, two military aircraft, and one official ship around Taiwan between 6 a.m. on Tuesday and the same time Wednesday.

The two People’s Liberation Army aircraft both crossed the median line and entered the country’s northern and southeastern air defense identification zone, according to the MND. In response, Taiwan deployed aircraft, naval ships, and coastal-based missile systems to monitor the PLA activity.

So far this month, the defense ministry has tracked Chinese military aircraft 35 times and ships 62 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.

Gray zone tactics are defined 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.”