China seems to be rapidly constructing reinforced aircraft hangars on the disputed artificial islands in the South China Sea (SCS), according to imagery recently released by the Washington-based Center for Strategic and International Studies (CSIS).
The satellite photographs, taken in late July, show that the hangars on Fiery Cross, Subi and Mischief reefs can station any type of aircraft currently in use by the Chinese air force.
Experts believe the rapid pace of construction could allow China to deploy dozens of fighter jets on the islands, effectively turning them into military installations.
The images were published weeks after an international tribunal ruled that China breached international law in a dispute over control of the SCS, thus dealing a blow to Beijing's expansive territorial claims in the region.
"China's goal seems to be to establish de-facto control over the water and airspace within the nine-dash line, at least vis-à-vis its Southeast Asian neighbors during peacetime," Gregory Poling, the director of the Asia Maritime Transparency Initiative at CSIS, told DW.
"Forward-deployed air assets are key to that plan," he added.
Asserting de facto power
This view is shared by Zachary Abuza, a Southeast Asia security expert and professor at the Washington-based National War College. He says China may have lost the legal case, but is now trying to assert its de facto control over the entire SCS.
"The deployment of military forces to the islands is one part of that. But the large harbors give the Chinese Coast Guard and their maritime forces the ability to patrol the waters and deny other countries the right to access or exploit resources 365 days a year," he told DW.
"This will remain the primary means by which China tries to enforce its sovereign claims."
China has wrangled with ASEAN countries like the Philippines, Vietnam, Malaysia and Brunei over the resource-rich SCS in a bitter territorial spat that has flared on and off for decades. China has claimed most of the sea, through which around $5 trillion in maritime trade passes every year, while the other countries have competing claims.
In an attempt to bolster its assertions, Beijing has been carrying out land reclamation projects and building artificial islands by piling sand on top of reefs and coral atolls. On top of these man-made islands, it has been constructing airstrips and ports, which many suspect could be used for military purposes. The US also believes that China's island-building could threaten navigation within the disputed area.
Court ruling puts little to rest
China, however, has insisted that it has no intention of militarizing the disputed maritime area, arguing instead that the artificial islands are aimed at "promoting public service" in the region by aiding ships, fishermen and disaster relief efforts.
Still, satellite images released by ImageSat International earlier this year showed that Beijing had deployed the advanced HQ-9 surface-to-air missile system to the Woody Island - part of the contested Paracel Islands in the SCS.
To counter Beijing's moves and reassure its Asian allies, the US has vowed to continue its freedom of navigation operations (FONOPs), sending military ships and aircraft near China's artificial islands.
Washington has also called on Beijing to respect the verdict of the Permanent Court of Arbitration (PCA) in The Hague, which last month ruled in favor of the Philippines and quashed China's claims to a strategic set of islands in the sea.
Nevertheless, China - which boycotted the PCA proceedings saying it had no jurisdiction over the matter - has maintained that it will ignore the ruling.
Meanwhile, many worry about the potential ramifications of the growing militarization of the region.
Quoting unidentified Western officials, Reuters recently reported that Vietnam had sent new mobile rocket launchers to some of the islets it holds in the region. The report said that they are capable of striking China's installations on the artificial islands.
However, it added, Vietnam's foreign ministry said the intelligence was "inaccurate," without elaborating.
"The reports are unconfirmed, but if they are true, then the most likely explanation is that Vietnam is moving to establish whatever defense capabilities it can, given the rapid construction of Chinese military infrastructure on its artificial islands," said Southeast Asia expert Poling.
Vietnam is clearly concerned that China could unilaterally declare an Air Defense Identification Zone (ADIZ) in the region, analysts point out.
Hanoi also wants to maintain an effective deterrent against Beijing, Abuza said. "Vietnam's aim is to show China that it does have the capabilities and will to respond should China try to seize or simply siege Vietnamese-held features."
To reduce tensions and militarization in the region, Abuza noted, there's a need to raise the costs to Beijing, in terms of diplomacy, trade, and security, of its current actions.
Furthermore, he calls on the international community to continue holding FONOPs and to build up the naval and maritime law enforcement capabilities of other SCS claimants.
But Poling stressed that the only option left for other states is to try to shine a spotlight on what is happening in order to ensure that China bears some level of diplomatic and reputational cost.
"Beyond that, there is nothing anyone can do to prevent Beijing from deploying air assets or other military equipment to these artificial islands if it is committed to doing so," he said.