Antelope Reef is a feature in the Paracel Islands, a disputed archipelago in the South China Sea claimed by China, Vietnam and Taiwan. Satellite images from September 25 show China building a full-scale runway there, with grading work, gravel piles, concrete and compaction cranes.

Analysts say the project could be completed by mid-2027. Based on China’s earlier build at Fiery Cross Reef in the Spratlys, which got a 3-km runway in 2015, experts expect paving in the first half of 2027 and a first landing by mid-2027.

A completed base at Antelope would be China’s most significant military expansion in the South China Sea in a decade. It would extend the reach of Chinese naval ships and military aircraft across a waterway that carries a large share of global trade and is an increasingly militarised arena of competition between Beijing and the United States and its allies over Taiwan.

China has yet to acknowledge a military base, with state media saying the site will serve civilian needs like weather forecasting and maritime research. Its defence ministry did not respond to Reuters’ request for comment.