The frequent muscle flexing by some countries in the South China Sea is the biggest cause for the militarization of the region, the Foreign Ministry said on Wednesday in response to a joint statement made by US and Australian foreign and defense ministers.

The facilities constructed on the reefs of the Nansha Islands are mostly for civilian use, aiming to better serve coastal nations in the South China Sea and passing vessels from around the world, Foreign Ministry spokeswoman Hua Chunying told a news conference.

"Of course, there are also some necessary military facilities, which are purely for self-defense purposes, and they are also limited," she said, adding that the construction of the facilities is to meet the requirements of China's safety, and China has not militarized the reefs.

Building necessary military facilities does not mean the region is being militarized, and it's understandable that China is deploying some military facilities for self-defense purposes because some countries have flexed their muscles in the South China Sea region, she added.

The spokeswoman's remarks came in response to a statement by the US and Australia that expressed "strong concerns over recent Chinese land reclamation and construction activity in the South China Sea". The statement called on "all claimant states to halt land reclamation, construction and militarization".

Saying that China has paid attention to the statement, Hua reiterated China's undisputed sovereignty over the Nansha Islands and the waters nearby.

"We need to point out that some countries have deployed a great many offensive weapons in places that are far from their homeland, and they have flexed their muscles frequently in the South China Sea region recently," she said. "This is the biggest cause that has pushed the 'militarization' of the South China Sea."

Those countries should stop playing up the South China Sea issue and keep their promise of not taking sides on territory issues, she said.

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