Three China Coast Guard (CCG) vessels on Sunday patrolled territorial waters near the Diaoyu Islands, according to the State Oceanic Administration (SOA).
The Japan Coast Guard monitored the operation, Kyodo news agency reported, adding that it marked the 32nd operation in 2015.
China has been conducting patrols on a regular basis. The SOA reported a patrol operation by three CCG vessels on Monday.
The territorial dispute over the Diaoyu Islands has soured relations between China and Japan since 2012 when Japan "nationalized" the islands.
The People's Liberation Army (PLA) Air Force sent H-6K bombers and other types of warplanes to fly over the Miyako Strait for high-sea training over the West Pacific Ocean on Friday, according to air force spokesperson Shen Jinke.
Shen said that the warplanes and airborne early warning aircraft simultaneously patrolled the Air Defense Identification Zone (ADIZ) over the East China Sea.
It's normal for coastal nations to use planes for high-sea training, and it was the fourth such exercise in 2015, and has improved the force's long-distance combat abilities, Shen noted. He added that the air force's strategic capabilities should be in keeping with national interests, the Xinhua News Agency reported.
