China will have three regiments of combat aircraft in South China Sea
China is has nearly completed build up of missile shelters, radar/communications facilities, and other infrastructure on Fiery Cross, Mischief, and Subi Reefs. In February, AMTI (Asian Maritime Initiative, CSIS) identified eight hardened shelters with retractable roofs at each of the Big Three, which Reuters had earlier reported would house missile launchers. China has now built four additional shelters at Fiery Cross.
The US military has had numerous close passes of the islands to show the US exercises freedom of navigation. A U.S. destroyer came within 12 nautical miles of a Chinese holding in the South China Sea a few weeks ago. The US sail bys have been part of Obama and Trump administration policies. The US ships can closely watch China build bases and put missiles and planes on the islands.
China will also be building up Woody island, Duncan island and Triton island in the Paracel area north of the south china sea.
In February, 2017, China had 20 outposts in the Paracels. Three of these now have protected harbors capable of hosting large numbers of naval and civilian vessels. Four others boast smaller harbors, with a fifth under construction at Drummond Island. Five of the islands contain helipads, with Duncan Island housing a full helicopter base. And the largest of the Paracels, Woody Island, sports an airstrip, hangars, and a deployment of HQ-9 surface-to-air missile batteries.
SOURCES- Asian Maritime Initiative, CSIS, Getty, Reuters, USNI