China said on Friday that it was monitoring US military activities in the disputed waters of the South China Sea. This latest statement comes after two U.S. bombers conducted training flights over the conflicted waterway.
The US Pacific Command announced on its website that two US Air Force B-1B Lancer bombers was on a 10-hour training mission from Guam over the South China Sea on Thursday. The mission was organized in conjuction with the Navy's USS Sterett guided-missile destroyer.
In late May, a US warship carried out a "maneuvering drill" within 12 nautical miles of an artificial island built up by China in the South China Sea. At that time, the US officials said that the military conducts such "freedom of navigation" patrols to show China it is not entitled to territorial waters there.
According to reports, the latest exercise was a part of Pacific Command's "continuous bomber presence" program. However, it did not reveal any further details about where the drill was conducted and it did not refer to it as a freedom-of-navigation operation.
Referring to the United States, the ministry said in a statement: "China always maintains vigilance and effective monitoring of the relevant country's military activities in the South China Sea."
"China's military will resolutely safeguard national sovereignty, security and regional peace and stability," the statement added.
China claims nearly whole of the strategically vital waterway, despite partial counter-claims from several regional states such as the Philippines, Brunei, Malaysia, Taiwan and Vietnam. About $5 trillion in ship-borne trade passes each year through the disputed waterway.
The United States has criticized China for its construction of islands and build-up of military facilities there. It is concerned that they could be used to restrict free movement and extend China's strategic reach.
U.S. allies and partners in the region had grown anxious as the administration of U.S. President Donald Trump had held off on carrying out South China Sea operations during its first few months in office.