CSIS AMTI: China's Antelope Reef Artificial Island Now Potentially Largest in South China Sea — ~1,490 Acres with 9,000-Ft Airstrip Footprint; First Major Island-Building Since 2017

A CSIS Asia Maritime Transparency Initiative (AMTI) analysis confirmed by mid-May 2026 that China has been conducting its first major artificial island construction in the South China Sea since 2017, at Antelope Reef (Lingyang Jiao) in the Paracel Islands. Satellite imagery and analysis published in late April and early May 2026 documented reclamation at Antelope Reef reaching approximately 1,490 acres — potentially making it the largest artificial island in the South China Sea, surpassing Mischief Reef (approximately 1,504 acres, the current largest in the Spratlys) and potentially surpassing all other Chinese-constructed features in the region. The outer landmass has a straight northwestern edge consistent with a future 9,000-foot (2,743m) airstrip, significantly longer than the 3,000m runways at Fiery Cross, Subi, and Mischief Reefs, and capable of accommodating heavier bomber and tanker aircraft including the H-6N and H-6K. AMTI documented over 50 grey-roofed structures on the landmass, a helipad, jetties, and foundations potentially for surface-to-air missile batteries and anti-ship cruise missile emplacements consistent with the militarization pattern at the three major Spratly bases. The accelerated construction coincided with a documented approximately 30% drop in US reconnaissance flight operations over the South China Sea — which analysts at Asia Times (April 4, 2026) attributed to US carrier strike group reallocation to the Middle East in connection with the Iran conflict. Vietnam filed a formal diplomatic protest on March 23, 2026, asserting Vietnamese sovereignty over the Paracel Islands (seized by China in 1974). China treats the Paracels as sovereign Chinese territory 'not in dispute.' The Antelope Reef construction represents the most significant Chinese artificial island project since the 2013-2016 Spratly Islands campaign that created Fiery Cross, Subi, and Mischief Reefs; its potential runway capable of supporting heavy bombers could significantly extend Chinese air-strike reach into the Indian Ocean, Bay of Bengal, and toward Australia — adding a new strategic dimension to the South China Sea militarization that AUKUS was designed to counter.