China is almost ready to operationalise dozens of aircraft hangars and high-end radar facilities on artificial islands in the disputed South China Sea, which experts say could help Beijing establish a controversial Air Defense Identification Zone in the area.

According to new satellite imagery released by a US-based think tank show nearly completed defense infrastructure on Fiery Cross, Mischief and Subi reefs, three of China's largest artificial islands in the disputed Spratly chain.

Each of the islands has new aircraft hangers, capable of holding 24 military aircraft, as well as several larger hangars that can hold bombers or surveillance planes, according to the images released by the Asia Maritime Transparency Initiative, AMTI.

The new facilities will further establish China's military dominance over the highly contested region, experts told CNN, and could help China establish a controversial Air Defense Identification Zone (ADIZ) in the area.

Chinese Ministry of Foreign Affairs spokeswoman Hua Chunying said today she was not aware of the report's details but reiterated the Spratly Islands were Chinese territory.

"Whether we decide to deploy or not deploy relevant military equipment, it is within our scope of sovereignty. It's our right to self-defense and self-preservation as recognised by international law," Hua said.

Fiery Cross, Mischief and Subi reefs are the largest of seven artificial islands built by China in the Spratlys. China claims the majority of the South China Sea as its territory, despite overlapping claims by a number of other Southeast Asian countries, including the Philippines and Vietnam.

Four bigger hangars have already been completed on Subi Reef, as well as another four on Fiery Cross Reef, the AMTI said, citing imagery taken this month.
Hangars to accommodate five larger planes, such as bombers, were in the final stages of construction on Mischief Reef.

"China's three military bases in the Spratlys and another on Woody Island in the Paracels will allow Chinese military aircraft to operate over nearly the entire South China Sea," AMTI said in a statement.

In addition to the hangars, new radar domes are in various stages of construction on each artificial island, about three arrays on each reef. Fiery Cross, Subi and Mischief reefs now all also have shelters for mobile missiles launchers, according to AMTI.

The establishment of an Air Defense Identification Zone, dubbed ADIZ, in the South China Sea has long been considered a possibility by analysts, especially in the wake of July's international court decision against China's maritime claims.

China declared its East China Sea ADIZ in November 2013, antagonising Japan and the United States, who both said they did not recognise it.

A similar zone in the South China Sea could rapidly increase tensions in the region, CNN quoted experts as saying.

"The worry has to be that if China bases its military aircraft (in the South China Sea), they could fly up and challenge anyone's military aircraft or civilian aircraft if they wanted to," said Carl Thayer, regional security analyst and emeritus professor at the University of New South Wales.

China had very rarely enforced its previous ADIZ, and any new zone in the south sea would start out as mostly "symbolic," Ian Storey, a senior fellow at the Institute of Southeast Asian Studies Yusof Ishak Institute, said.

"And the US will ignore it as it did with the East China Sea ADIZ," he said. "The interesting question is really how the Southeast Asian states will respond."
Though the infrastructure is almost ready, no military aircraft has been deployed to the islands yet, Storey said.

China's next step would be to very slowly deploy planes to the artificial islands to gauge the local and US response, Thayer said.