"I want to reiterate that China building facilities, including deploying necessary and appropriate national defense installations in its own territory, is exercising our sovereign right recognized by international law," Geng said.

"We hope other countries respect our efforts and do more to help preserve peace and stability in the region."

"The ASEAN ministers have been unanimous in their expression of concern about what they see as the militarization of the region," Philippine Foreign Secretary Perfecto Yasay told reporters, using the acronym for the group of Southeast Asian countries.

"In so far as certain reclamation of certain features built on the South China Sea that had been completed, they (ASEAN ministers) have noticed, very unsettlingly, that China has installed weapons systems in these facilities that they have established."

Disputed waters

The move comes amid growing tensions between China and the United States as President Donald Trump has shown himself more willing to take a confrontational stance with Beijing than his predecessor.

In a news conference last week, China's Foreign Ministry said it heard about the planned deployment of the Vinson days before it happened and warned Washington against challenging its sovereignty.

"China respects and upholds the freedom of navigation and overflight in the South China Sea, which countries enjoy under international law, but firmly opposes any country's attempt to undermine China's sovereignty and security in the name of the freedom of navigation and overflight," the Chinese Foreign Ministry spokesman said at the time.

Dotted with small islands, reefs and shoals, the South China Sea is a crucial shipping route and home to a messy territorial dispute that pits multiple countries against one another.

Tensions in the disputed waters have ratcheted up since 2014 as China has turned sandbars into islands, equipping them with airfields, ports and weapons systems and warned US warships and aircraft to stay away from them.