BEIJING China's navy and civilian maritime patrol vessels practiced on Friday stopping "illegal entry" into Chinese waters in the East China Sea, state media said, an area where Beijing is embroiled in a territorial dispute with Japan.
State news agency Xinhua said the drill was the largest in recent years, made up of 11 vessels, eight aircraft and more than 1,000 sailors.
While the report made no mention of tensions with Japan over a group of uninhabited islands in the East China Sea, it left little doubt the maneuvers were aimed at sending a message to Tokyo.
"The drill included simulations of illegal entry, obstruction, harassment and intentional interference by foreign vessels when Chinese ships of the fishery administration and marine surveillance agency patrolled," Xinhua said.
The exercise, it said, "was aimed at improving coordination between the navy and administrative patrol vessels, as well as sharpening their response to emergencies in order to safeguard China's territorial sovereignty and maritime interests".
Japanese Defense Minister Satoshi Morimoto, quoted by his ministry's Internet site, said he would not comment on the nature or purpose of the exercises.
But he added in comments to reporters: "Regardless of their activities, we remain vigilant in the waters and airspace where our country is in charge."
Chinese fishery patrol ships and Japan's coast guard have faced off in recent weeks in the seas around what China calls the Diaoyu Islands and Japan the Senkaku islands. Taiwan also claims them.
Violent protests and calls for boycotts of Japanese products broke out across China in mid-September after Japan bought some of the islets from their private owner.
(Reporting by Ben Blanchard and by Kiyoshi Takenaka in Tokyo; Editing by Ron Popeski)