BEIJING, March 26 (Xinhua) -- A spokesperson for China's Ministry of National Defense on Thursday urged the U.S. side to stop taking provocative and dangerous acts to avoid serious damage to the relations between the two countries and the two militaries.

Spokesperson Ren Guoqiang made the remarks while commenting on the operations of the U.S. Navy P-8A reconnaissance aircraft on Feb. 17, which ignored multiple warnings of the Chinese side and approached a Chinese navy fleet conducting routine drills on the high seas.

The reconnaissance lasted for over four hours, and the aircraft's minimum distance to the Chinese fleet was only about 400 meters, Ren said, calling the operations extremely "unprofessional and unsafe."

For a long time, the U.S. side has been conducting close-range and long-lasting surveillance of Chinese ships and aircraft, creating disturbances, said Ren.

The provocative acts of the U.S. side damaged China's security interests and endangered the officers and soldiers of both sides, Ren said, noting that such acts undermined and abused the free navigation rules of international laws.

These acts are the root of maritime safety problems between China and the United States, said Ren.

The Chinese side firmly opposes such moves, Ren said, urging the U.S. side to stop the acts as well as stop discrediting China.