BEIJING (Reuters) – China’s air force has carried out exercises near the Korean peninsula, practicing to defend against a “surprise attack” coming over the sea, Chinese state media reported.

An anti-aircraft defense battalion carried out the exercises early on Tuesday, near the Bohai Sea, the innermost gulf of the Yellow Sea that separates China from the peninsula, an official military website www.81.cn reported.

Troops traveled to the site from central China before immediately beginning drills to fend off the “surprise attack” simulating real battle, it said.

“The troops rapid response capabilities and actual combat levels have effectively been tested,” it said.

It was the first time certain weapons, which it did not identify, had been used to shoot down low-altitude targets coming over the sea, www.81.cn said, without elaborating.

China’s Defence Ministry did not immediately respond to a faxed request for comment.

The exercise came days after North Korea carried out its sixth and largest nuclear test of an advanced hydrogen bomb and there is mounting concern internationally that the country plans more weapons tests, possibly of a long-range missile.

After weeks of rising tension, South Korea and the United States have been discussing the deployment of aircraft carriers and strategic bombers to the Korean peninsula.

China is deeply suspicious of any U.S. backed military build up in the region and has repeatedly expressed anger at the deployment of a U.S. anti-missile defense system in South Korea.

(Reporting by Christian Shepherd)