China on Friday reacted to news that two US Air Force bombers had flown over the  South China Sea.

The US military said Thursday that two B-1B bombers had flown a 10-hour mission from Guam in an operation with a Navy guided-missile destroyer.

Asked about this at a press conference on Friday, China's Ministry of National Defense said China was on alert and keeping effective supervision of military actions by other countries around the South China Sea.

Chinese People's Liberation Army will firmly protect the safety of national sovereignty and regional peace and stability, it added.