China's military sent several fighter jets and an early warning aircraft on patrol into disputed air space over the East China Sea on Thursday, the Chinese state news agency Xinhua reported, quoting a spokesman for the People's Liberation Army Air Force.
The move raises the stakes in a standoff with the United States, Japan and South Korea over the zone. Japan and South Korea sent their own military aircraft through the air space on Thursday.
(Read more: US cautions airlines flying over East China Sea)
The Chinese patrol mission was "a defensive measure and in line with international common practices," said Shen Jinke, a spokesman for China's air force, in the Xinhua article.
Ties between China and Japan have been strained for months by the dispute over the islands in the East China Sea, called the Diaoyu by China and the Senkaku by Japan. The islands are currently under Japanese administrative control.