Signalling a possible further militarization of the region, China has placed advanced surface-to-air missiles on one of its claimed islands in the South China Sea.

Beijing placed two batteries of eight surface-to-air Hongqi-9 (HQ-9) missiles on Woody Island, which is part of the disputed Paracel Island chain in the disputed waters.

Although this is not the first time that China has placed weapons on the island chain, the technical abilities of the missiles combined with Beijing’s overall more aggressive policy in the region is a potential game changer.

“Our analysis of the imagery released indicates China has deployed a fourth-generation SAM system to the South China Sea. This represents a significant military escalation. This leapfrogs steps such as deploying shorter-range systems and increasing the tempo of visits by military aircraft to the islands,” writes Neil Ashdown, the Deputy Editor of IHS Jane’s Intelligence Review.

“However, the deployment is still less significant from a military perspective for the US and others than the deployment of systems such as the YJ-type anti-ship cruise missiles.”

Still, the deployment is meant as a signal to the US and likely to other nations throughout the region that China is serious about backing up its claims to the region and intends of fully taking control of the islands that it has claimed.

“Woody Island is being turned into a forward-operating base,” Richard Bitzinger, a defence expert at the S. Rajaratnam School of International Studies told GlobalPost. “They’re trying to turn it into a proper garrison.”

And the use of HQ-9s for this mission is telling. The weapons are one of the most advanced weapons in China’s arsenal. according to Bitzinger.

The missiles are largely constructed from a mix of Chinese domestic systems and reverse engineered Russian S-300 and US Patriot missile system technologies. This allows the HQ-9 to track, target, and intercept both aircraft and incoming missiles, Missile Threat, a project of the George C. Marshall and Claremont Institutes, notes.

The HQ-9, Missile Threat reports, includes modified versions of the propulsion and guidance systems from US Patriot Missiles.

Peter Goon, of the think tank Air Power Australia, has a direct assessment of what the HQ-9 missiles are for.

“They’re principally for killing aircraft,” he told GlobalPost.

In total, the missiles have a range upwards of 125 nautical miles, which would grant a large defensive radius to China’s activities in the Paracel Islands as well as to the Chinese island of Hainan. Hainan, which is just over 200 miles away from Woody Island, is quickly taking on new importance for the Chinese military.

Beijing is expanding its naval presence at the city of Sanya on Hainan, and the HQ-9s are likely there to help protect the island’s flank, The New York Times reports.

The decision to place the missiles on the island comes after China told the US it agreed to not militarize the South China Sea. However, Beijing sees the Paracels as its own domestic territory, and has defended the placement as in accordance with international law, the Times notes.

“We’re starting to see rapidly changes in the balance of power between China and the West so, really, it was not unexpected that the Chinese would move these [missile] capabilities down there,” Goon told GlobalPost. “Historically, they have always seen the South China Sea as their front yard.”

Goon’s assessment is echoed by a recent report by the Center for Strategic and International Studies. The think tank notes that by 2030 the South China Sea will essentially exist as a “Chinese lake” due to Beijing’s focus on acquiring submarines and aircraft carriers, alongside its continued development and militarization of islands in the region.

Currently, the various islands and atolls in the South China Sea are claimed and disputed in a various mix principally by Taiwan, Vietnam, China, the Philippines.

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