BEIJING (REUTERS) - China's Defence Ministry said on Tuesday (July 25) that its pilots' actions were legal, necessary and professional after two Chinese fighter jets intercepted a US Navy surveillance plane over the East China Sea at the weekend.
The ministry said in a statement that the US plane threatened China's national security and urged the United States to immediately cease such military activities.
US officials had said on Monday that one of the Chinese jets came within about 90m of the American aircraft.
The officials, speaking on condition of anonymity, said initial reports showed one of the Chinese J-10 aircraft came close enough to the US EP-3 plane on Sunday (July 23) to cause the American aircraft to change direction.
One official said the Chinese jet was armed and the interception happened at about 148km from the Chinese city of Qingdao.
The Pentagon said the encounter between the aircraft was unsafe, but added that the vast majority of interactions were safe.
China's Defence Ministry said on Tuesday the actions of its pilots were "legal, necessary and professional" and performed "in accordance with the law and the rules".
"Close-in reconnaissance by US aircraft threatens China's national security, harms Sino-US maritime and air military safety, endangers the personal safety of both sides' pilots and is the root cause of unexpected incidents," it said.
The US should immediately stop these military activities, which are unsafe, unprofessional and unfriendly, it added.
Incidents such as Sunday's interception are relatively common.
In May, two Chinese SU-30 aircraft intercepted a US aircraft designed to detect radiation while it was flying in international air space over the East China Sea.
China closely monitors any US military activity around its coastline.
In 2001, an interception of a US spy plane by a Chinese fighter jet resulted in a collision that killed the Chinese pilot and forced the American plane to make an emergency landing at a base on Hainan.
The 24 US air crew members were held for 11 days until Washington apologised for the incident. That encounter soured US-Chinese relations in the early days of President George W. Bush's first term in office.
Separately, the Pentagon said the US military would soon carry out another test of its Terminal High Altitude Area Defence (Thaad) system.
"These tests are done as a routine measure to ensure that the system is ready and... they are scheduled well in advance of any other real-world geopolitical events going on," Pentagon spokesman Jeff Davis told reporters.
The director of the Missile Defence Agency, Lieutenant-General Sam Greaves, said in a statement that a test would be carried out at the Pacific Spaceport Complex in Alaska.
Last month, the US shot down a simulated, incoming intermediate-range ballistic missile similar to the ones being developed by countries such as North Korea, in a test of the nation's Thaad missile defences.
The US deployed Thaad to South Korea this year to guard against North Korea's shorter-range missiles. That has drawn fierce criticism from China, which says the system's powerful radar can penetrate deep into its territory.