China has called on the US to stop close reconnaissance activities after the Pentagon said two Chinese fighter jets intercepted a US military aircraft over the South China Sea.
Foreign Ministry spokesman Hong Lei told reporters Thursday that the Chinese aircraft kept a safe distance from the US plane, which was flying close to China's island province of Hainan.
Hainan is a military area of increasing sensitivity for China. Its bases on Hainan are home to an expanding fleet of nuclear-armed submarines and a big target for ongoing Western surveillance operations.
The Guangdong coast is also believed to be home to some of China's most advanced missiles, including the DF-21D anti-ship weapon.
"We demand that the United States immediately cease this type of close reconnaissance activity to avoid having this sort of incident happening again," Hong said.
The Pentagon said on Wednesday Chinese jets carried out an “unsafe” intercept of its aircraft, which was conducting “a routine US patrol” in international airspace.
It said two Chinese J-11 fighters flew within about 15 meters (50 feet) of the EP-3 Aries on Tuesday, forcing the US pilot to descend sharply to avoid a collision.
Hong said the actions of the Chinese aircraft were "completely in keeping with safety and professional standards."
"They maintained safe behavior and did not engage in any dangerous action," he said.
The incident comes a week after China scrambled fighter jets as a US Navy ship sailed close to a disputed reef in the South China Sea.
Tensions are rising before President Barack Obama travels to parts of Asia from May 21-28, which will include a Group of Seven summit in Japan and his first trip to Vietnam.
The South China Sea has become a source of tension between China, the US, and other countries seeking control of trade routes and mineral deposits there.
China claims most of the South China Sea, through which $5 trillion in ship-borne trade passes every year.
Being has on different occasions asserted its sovereignty over the sea, parts of which are also claimed by Brunei, Malaysia, Taiwan, Vietnam and the Philippines.
Washington has accused Beijing of attempting to take advantage of the dispute and gradually asserting control over the region.
China rejects the allegations and says the US is interfering in regional affairs and deliberately stirring tensions in the South China Sea.
In April 2001, an intercept resulted in a collision that killed a 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 apologized for the incident. The encounter soured ties in the early days of President George W. Bush's administration.
Last month, the Pentagon said that Russia had intercepted a US Air Force aircraft over the Baltic Sea in an "unsafe and unprofessional" way.