New satellite imagery shows China has apparently installed "significant" defensive weapons on a series of artificial islands it built in the South China Sea, a Washington think-tank said Wednesday.
Beijing has created seven islets in the Spratly Islands in recent years, built up from smaller land protuberances and reefs.
Although Beijing insists it does not wish to militarize the contested waters of the South China Sea, ongoing satellite imagery has shown the installation of military equipment and longer runways.
The latest images, released by the Asia Maritime Transparency Initiative (AMTI), show a series of hexagonal structures now in place on each of the seven islets.
They appear to be large anti-aircraft guns and close-in weapons systems (CIWS), AMTI said.
"These gun and probable CIWS emplacements show that Beijing is serious about defense of its artificial islands in case of an armed contingency in the South ChinaSea," said AMTI, part of the Center for Strategic and International Studies.
"Among other things, they would be the last line of defense against cruise missiles launched by the United States or others against these soon-to-be-operational air bases."
Johnson Reef, November 29, 2016. Source: Asia Maritime Transparency Initiative
The South China Sea issue has been brewing for years, with China, the Philippines, Brunei, Malaysia and Vietnam all making competing claims in waters with vital global shipping routes and what's believed to be significant oil and gas deposits.
Beijing's territorial claims, based on controversial historical records, have also pitted it against Washington.
China paused land-reclamation efforts last year and began focusing on "infrastructure development" of the islets, according to a Pentagon report in May.
The United States insists China's claims have no basis under international law, and the US military has conducted several "freedom of navigation" operations in which ships and planes have passed close to the sites Beijing claims.
Such missions have drawn howls of fury from China, which accuses the United States of provocation and increasing the risk of a military mishap.
The Permanent Court of Arbitration in The Hague in July ruled there was no legal basis to China's claims to nearly all of the South China Sea, a verdict Beijing dismissed.
