A Chinese fighter jet intercepted a U.S. Air Force RC-135 reconnaissance plane over the East China Sea in a maneuver characterized as “unsafe,” the United States Pacific Command said Wednesday. The intercept, which involved two Chinese J-10 fighter planes and the U.S. spy plane, was conducted Tuesday in international airspace.

"One of the intercepting Chinese jets had an unsafe excessive rate of closure on the RC-135 aircraft. Initial assessment is that this seems to be a case of improper airmanship, as no other provocative or unsafe maneuvers occurred," the Pacific Command reportedly said, in a statement. However, it did not mention how close the Chinese fighter came to the U.S. plane.

"The Department of Defense is addressing the issue with China in appropriate diplomatic and military channels," it said. 

China's Defense Ministry reportedly said it was looking into the report of the "unsafe" intercept. 

"Judging by the report, the U.S. side is again deliberately hyping up the issue of the close surveillance of China by U.S. military aircraft," it said in a statement sent to Reuters. "Chinese military pilots consistently carry out operations in accordance with the law and the rules, and are professional and responsible."

In May, the Pentagon said that two Chinese fighter jets flew within 50 feet of a U.S. EP-3 aircraft over the South China Sea.

“Initial reports characterized the incident as unsafe,” Lt. Col. Michelle Baldanza, a Pentagon spokeswoman, said in a written statement to NBC News, adding, “Over the past year, DoD has seen improvements in PRC [People’s Republic of China] actions, flying in a safe and professional manner.”

The South China Sea has been long debated, with Beijing laying claim to most of the region. Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have conflicting claims to the waters, through which over $5 trillion of maritime trade passes annually. China has been expanding its presence in the region and has built three runways on the Spratly archipelago.

The United States has been conducting sea and air patrols near artificial islands that China is constructing in the disputed Spratly archipelago. The U.S. says its freedom of navigation operations are designed to emphasize that the South China Sea, home to some of the world’s busiest shipping lanes, remains international waters, asserting that it would increase the "freedom of navigation" sail-bys around the disputed area.