China’s military has stepped up activity around Taiwan this week, sending dozens of warplanes across the median of the Taiwan Strait and into key areas of the island’s air defense identification zone (ADIZ), CNN reports.

The People’s Liberation Army (PLA) activity has a number of implications, none of them positive for Taiwan or cross-strait stability, analysts say.

According to data from Taiwan’s defense ministry, 38 Chinese aircraft were spotted around the island on Wednesday, 33 on Thursday and 30 on Friday.

During those 72 hours, 73 Chinese aircraft either crossed the median line of the strait, an informal demarcation point that Beijing does not recognize but until recently largely respected, or entered the island’s southeastern or southwestern zone of recognition.

China’s ruling Communist Party claims the self-governing republic of Taiwan as its territory, even though it has never controlled it, and has spent decades trying to isolate it diplomatically. Beijing has not ruled out using force to take control of the island.

This week’s military activity included fighter jets, H-6 bombers, anti-submarine warning aircraft and reconnaissance drones, Taiwan’s defense ministry said.

The ministry said it tasked combat patrol warplanes, naval vessels and ground-based missile defense to monitor the Chinese aircraft, as well as nine Chinese warships located around the island.