"Our law enforcement vessels patrolled waters close to the Diaoyu Islands to maintain normal order and safeguard China's maritime rights and interests," spokesman Liu Weimin said during a routine press conference.
Liu reiterated that the Diaoyu Islands and its adjacent islets are part of China's territory.
The State Oceanic Administration issued a statement Friday saying that two of its surveillance ships, the Haijian 50 and Haijian 66, arrived in the area early Friday morning to begin regular patrols.