Two People’s Liberation Army Air Force (PLAAF) Shenyang J-16 fighter jets and one Shaanxi Y-8 electronic warfare aircraft flew into the southwest corner of Taiwan’s ADIZ, according to the Ministry of National Defense (MND), Taiwan News reported.

In response, Taiwan sent aircraft, issued radio warnings, and deployed air defense missile systems to monitor the PLAAF planes, the newspaper reported.

Since September of last year, Beijing has stepped up gray zone tactics by routinely sending aircraft into Taiwan’s ADIZ, with most occurrences taking place in the southwest corner of the zone, reports Taiwan News.