China has flexed some maritime muscle in its dispute with Japan over a chain of uninhabited islands, holding naval exercises in the East China Sea to strengthen its response to threats to its territorial sovereignty.
Both countries have been displaying their naval prowess during a bitter dispute over the islands, called Diaoyu in Chinese and Senkaku in Japanese. Tokyo angered Beijing last month by nationalising some of the islands, a move that sparked violent protests in China.
The exercise involves 11 vessels from the East China Sea fleet and eight aircraft and will be coordinated with the marine surveillance agency and the fishery administration, the official Xinhua News Agency said.
Xinhua said patrol vessels from the fishery administration and the marine surveillance agency have recently been stalked and harassed by foreign vessels while carrying out missions.
On Tuesday, Japanese military aircraft spotted seven Chinese warships not far from the disputed islands. China said the ships were on a routine training mission.
Japan's navy marked its 60th anniversary on Sunday with a major exercise involving about 40 ships - including state-of-the-art destroyers, hovercraft able to launch assaults on rough coastlines and new conventionally powered submarines.
For the first time, Japan's navy was joined by warships from the United States, Singapore and Australia. Representatives from more than 20 countries, including China, attended the event staged in waters south of Tokyo.
Japan also plans to hold a joint exercise with the US military later this year, reportedly using a scenario of taking a remote island back from a foreign intruder.
Nearby Taiwan also claims the islands, which are uninhabited but surrounded by rich fishing grounds and possibly lucrative undersea energy deposits.
China's exercise also takes place after dozens of Japanese parliament members, including two Cabinet ministers, visited the controversial Yasukuni Shrine in Tokyo that honours 2.5 million war dead, but also commemorates 14 Japanese wartime leaders convicted of war crimes.