The deployment of the Russian S-400 surface-to-air missile system will substantially improve China's air defense capability, military experts said as Russian media reported that China has bought the cutting-edge weapon.

"The S-400 is definitely one of the top anti-aircraft weapons in the world. It will greatly supplement the People's Liberation Army's air defense system, which now has some loopholes in long-range, high-altitude defense of airplanes or ballistic missiles," said Wang Ya'nan, deputy editor-in-chief of Aerospace Knowledge magazine.

"The system has multiple types of missiles with various ranges, enabling it to safeguard a very large area of airspace. Some of its missiles are even specifically designed to intercept ballistic missiles," Wang said. "Moreover, some of its launch tubes can store and launch several different missiles, which makes it very convenient and fast to use."