China’s military has sent its Liaoning aircraft carrier and seven escort ships for training through the Miyako Strait — a key gateway into the Western Pacific Ocean that is closely monitored by Japan — according to the Defense Ministry in Tokyo.

The Chinese ships’ passage near Okinawa Prefecture and exercises in the Pacific are likely intended to check military activities in the area by the U.S., Japan and others, especially as the allies become increasingly vocal over the fate of self-ruled Taiwan.

The ministry said late Monday that the flotilla of warships had passed through the waterway that separates Okinawa’s main island from Miyako Island earlier in the day, and that six of the eight ships had first been detected about 350 kilometers southwest of Nagasaki Prefecture’s Danjo Islands on Sunday.