The Chinese government has nearly completed a 3km-long airstrip on a man-made island built to project military power into the South China Sea.
New photos taken by US aircraft show dozens of Chinese dredging vessels at work near the island in the Spratly archipelago.
The Asia Maritime Transparency Initiative at the Centre for Strategic and International Studies in Washington says that two helipads, ten satellite dishes, a Chinese Naval vessel and a radar tower are visible in the photo.
China claims most of the South China Sea as its own territory, though this is disputed by neighbouring nations including the Philippines, Vietnam, Malaysia, Brunei and Taiwan.
Last week the US State Department compared China’s policy in the South China Sea to that of Vladimir Putin’s Russia in eastern Ukraine.
Gallery: '50 years that changed China'
Show all 6“The way forward is for China, and all claimants, to freeze their reclamation activities and resolve their difference in accordance the rule of law,” Deputy Secretary of State Antony Blinken said.
“In both eastern Ukraine and the South China Sea, we’re witnessing efforts to unilaterally and coercively change the status quo — transgressions that the United States and our allies stand united against,”
Mr Blinken was speaking at a speech at the Center for a New American Security think tank.
China intensified efforts to construct the island last year.
The country’s government says the outposts have military, disaster relief, navigation, and search and rescue purposes.
Subscribe to Independent Premium to bookmark this article
Want to bookmark your favourite articles and stories to read or reference later? Start your Independent Premium subscription today.
Join our commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies