Japan has been following China's military drills around Taiwan consistently and "with great interest", a top government spokesperson said on Monday, on the last scheduled day for the exercises where Beijing has simulated striking the island.
China announced the three days of drills on Saturday, after Taiwan's President Tsai Ing-wen returned to Taipei following a meeting in Los Angeles with U.S. House of Representative Speaker Kevin McCarthy.
China claims democratically-governed Taiwan as its own territory and has never renounced the use of force to bring the island under Beijing's control.
Japan has long worried about China's military activities in the area given how close its southern islands are to Taiwan.
"The importance of peace and stability in the Taiwan Strait is not only important for the security of Japan, but also for the stability of the international community as a whole," Chief Cabinet Secretary Hirokazu Matsuno told reporters.
The southern Japanese island of Okinawa hosts a major U.S. air force base and last August when China staged war games to protest the visit of then-U.S. House Speaker Nancy Pelosi to Taipei Chinese missiles landed within Japan's exclusive economic zone.
The United States has said it is also watching China's drills closely.
China's military simulated precision strikes against Taiwan in the second day of drills around the island on Sunday.
The People's Liberation Army's Eastern Theatre Command on Monday released a short video on its WeChat account showing a nuclear-capable H-6 bomber flying in what it said was the skies to the north of Taiwan.
"The missiles are in good condition," an unidentified voice says, as the video shows images from the cockpit.
"Start the fire control radar, lock on the target," another voice says, showing images of a missile under the aircraft's wing.
It then shows a pilot readying the fire control button for what it describes as a simulated attack, and then pressing the button, though it did not show any missiles being fired.
Taiwan's military has been scrambling fighters and sending warships to shadow China's forces, but said it would respond calmly and not provoke conflict.
On Monday morning, releasing a map of the previous 24 hours Chinese air force activities, it showed fighters again crossing the sensitive median line of the Taiwan Strait as well as four carrier-based Chinese J-15 fighters operating over the Pacific Ocean to Taiwan's east.
While the ministry did not provide details, Taiwan said last week it was tracking the Chinese carrier the Shandong to its east.
The ministry separately released pictures on Monday of mobile launchers for the Taiwan-made Hsiung Feng anti-ship missiles at an undisclosed location, as well as missile-armed fast attack boats at sea.