State television broadcast images on Tuesday it said showed the East Sea Fleet on recent manoeuvres, including helicopters and a submarine launching a long-range missile underwater.
It did not say exactly where or when the pictures were taken and it was not clear if they showed a drill that the official Xinhua news agency said took place over the weekend.
Xinhua said four rescue helicopters and four rescue ships were deployed in the two-day drill in the Yellow Sea, where the United States and South Korea are planning manoeuvres aimed at sending a message of deterrence to North Korea.
Beijing has condemned those drills, which many in China feel are also aimed at their country.
Zhu Chenghu, a strategic studies professor at the National Defence University, told the China News Service that the U.S.-South Korean drills were clearly aimed at sending Beijing a message as much as they were directed at North Korea.