China's defense ministry criticized a U.S. report assessing its island-building efforts in the South China Sea, saying it "hyped up" China's so-called military threat.

The U.S. Defense Department's annual report on China's military activities had "wilfully distorted China's national defense policy," said ministry spokesman Yang Yujun, adding that the U.S. was too suspicious.

China expressed its "strong dissatisfaction and firm opposition" to the Pentagon report, Yang said.

"China follows a national defense policy that is defensive in nature," he said. "China's deepening military reforms and its strengthening of weapons and equipment building are aimed at maintaining sovereignty, security and territorial integrity and guaranteeing China's peaceful development."

The report to the U.S. Congress on Friday said that China was focused on developing and weaponizing the islands it has built in the disputed waters of the South China Sea so it will have greater control over the maritime region without resorting to armed conflict.

It accused China of "increasingly assertive efforts to advance its national sovereignty and territorial claims" and a lack of transparency about its growing military capabilities that are causing tensions with other countries in the region.

Yang said it was the United States that had been "frequently sending military aircraft and warships to the South China Sea to make a show of force."