China said Friday that it has been vigilant over the military activities of the countries in the South China Sea in reference to the US Rockwell B-1B heavy bombers that flew over the disputed water Thursday.
China's Ministry of National Defense(MND) said in response to news released by the US Pacific Command that two U.S. Air Force B-1B Lancer bombers flew a 10-hour training mission from Guam over the South China Sea on Thursday, in conjunction with the Navy's USS Sterett guided-missile destroyer.
The exercise comes after a U.S. warship in late May carried out a "maneuvering drill" within 12 nautical miles of an artificial island built up by China in the South China Sea.
The Information Office of China's MND responded that China always remains vigilant on the military activities of the related countries in the South China Sea, and those activities are under effective surveillance of China, China Military Online reported Friday.
He added that "the Chinese military will resolutely safeguard national sovereignty and security, and maintain regional peace and stability."
China claims nearly all of the South China Sea, through which about $5 trillion in ship-borne trade passes each year. However, its stance contested by Brunei, Malaysia, the Philippines, Taiwan and Vietnam.
The United States has criticized China's construction of islands and build-up of military facilities there. Further, they are concerned that they could be used to restrict free movement and extend China's strategic reach.