TAIPEI (Taiwan News) — Japan's Ministry of Defense on Tuesday published movements taken earlier this month by Chinese aircraft carriers Liaoning and Shandong southeast of Japan and east of Taiwan.

This marked the first time the two carriers operated simultaneously in the Pacific near Japan, per The Japan Times. Japan said it released the map due to the long duration of carrier activities.

The Joint Staff of Japan's Ministry of Defense said that the Liaoning passed through the waters between Okinawa's main island and Miyako Island in late May, continued to the waters east of the Philippines, then turned northeast. On June 7, it entered Japan’s Exclusive Economic Zone near Minamitorishima, Japan’s easternmost outlying island.

The Liaoning later turned westward, passing southwest of Okinotorishima on June 16. During this period, the carrier’s fighter jets and helicopters conducted approximately 550 takeoffs and landings.

On June 7, the Shandong traveled east toward waters southeast of Miyako Island, on June 8 began circling along the waters around and within Japan’s EEZ near Okinotorishima, and headed west on June 16. Carrier aircraft carried out around 230 takeoffs and landings during that time. 

Shandong aircraft reportedly approached Japanese Maritime Self-Defense Force patrol aircraft, coming as close as 45 meters on June 7 and 8. The Ministry of Defense on June 12 “expressed serious concern” over the incident to Beijing, per Reuters. 

As of Tuesday, both Chinese carriers were sailing westward in the Pacific toward China. Japan’s Ministry of Defense said it would maintain close surveillance.