China’s defense ministry is accusing the United States of a “serious military provocation” after two B-52 bombers flew over man-made Chinese-controlled islands in the South China Sea, according to The Associated Press

“The actions by the U.S. side constitute a serious military provocation and are rendering more complex and even militarizing conditions in the South China Sea,” the Defense Ministry said in a statement reported by AP.

ADVERTISEMENT

The ministry demanded the U.S. government take immediate steps to avoid similar incidents in the future.

The Stratofortress bombers flew over the islands Dec. 10, putting Chinese military personal on high alert. The heavy bombers can hold up to 50 500-pound bombs and 30 100-pound bombs. The plane was originally designed to deliver nuclear payloads.

"In the face of provocative acts from the U.S. side, the Chinese military will take all necessary means and measures to resolutely safeguard national sovereignty and security and resolutely safeguard regional peace and stability," the Chinese defense ministry said.

China has been locked in a dispute for decades with neighbors Taiwan, Vietnam and the Philippines over territory in the South China Sea, home to important shipping lanes and possibly rich troves of mineral resources.

China has built chains of manmade islands to bolster its disputed territorial claims.

Pentagon spokesman Mark Wright told the AP that the military planes may have wandered off course.

“The United States routinely conducts B-52 training missions throughout the region, including over the South China Sea,” he said. “These missions are designed to maintain readiness and demonstrate our commitment to fly, sail and operate anywhere allowed under international law.”