China launched two fighter planes Friday to investigate flights by a dozen U.S. and Japanese reconnaissance and military planes in its newly established maritime air defense zone over the East China Sea, state media said.

The state-run China News quoted Defense Ministry spokesman Col. Shen Jinke as saying the Chinese fighter jets identified and monitored the two U.S. and 10 Japanese aircraft during their flights through the zone early Friday, but made no mention of any further action.

China announced last week that all aircraft entering the zone — a maritime area between China, Taiwan, South Korea and Japan — must notify Chinese authorities beforehand, and that it would take unspecified defensive measures against those that don’t comply. Neighboring countries and the U.S. have said they will not honor the new zone and have criticized the move, saying it unnecessarily raises tensions.

It was the first time China said it sent military planes into the zone on the same day as foreign military flights since proclaiming the zone on Nov. 23.

The United States and other countries have warned that the new zone could boost chances for miscalculations, accidents and conflicts, though analysts believe Beijing’s move is not intended to spark any aerial confrontations but rather a long-term strategy to solidify claims to disputed territory by simply marking the area as its own.

The zone is seen primarily as China’s latest bid to bolster its claim over a string of uninhabited Japanese-controlled islands in the East China Sea known as Senkaku in Japan and Diaoyu in China. Beijing has been ratcheting up its sovereignty claims since Tokyo’s nationalization of the islands last year.

There are questions whether China has the technical ability to fully enforce the zone due to a shortage of early warning radar aircraft and in-flight refueling capability.

(AP)