AFP
The largest island is being constructed at the Fiery Cross Reef close to the Spratly Islands, an island chain whose territory is partially claimed by China, the Philippines, Vietnam, and Malaysia.
US officials estimated that the Chinese construction at Fiery Cross Reef could accommodate an airstrip long enough for most of Beijing's military aircraft. Beijing is also believed to be constructing a small port on the island.
China is also expanding man-made islands on Johnson South Reef, Johnson North Reef, Cuarteron Reef, and Gaven Reef around the Spratlys.
"China appears to be expanding and upgrading military and civilian infrastructure - including radars, satellite communication equipment, antiaircraft and naval guns, helipads and docks - on some of the man-made islands," the US-China Economic and Security Review Commission stated in a staff report from Dec. 2014.
Once the airstrip is operational, the staff report states, the Chinese military would likely use the airstrip as a launching point for aerial
The airstrip's presence is only likely to further tensions and distrust in the region, which is the site of several complex and overlapping territorial claims:
Mike Nudelman/Business Insider
Aside from China, Taiwan, Malaysia, Vietnam, and the Philippines already have airstrips on islands within the South China Sea.
The threat of Chinese superiority in the region has driven countries with oftentimes cold relations towards each other in an attempt to counter Beijing's growing reach - Vietnam and the Philippines have recently agreed to increase military ties in the region.
"We already have joint training and exercises with the US military every year and we are looking forward to hold exercises with the Vietnamese navy," an unnamed Philippine navy officer told Reuters.
Vietnam will be the the Philippines' third strategic partner in the region after the US and Japan.
The US is also looking towards Japan to play a larger role in air patrols in the South China Sea. Japanese aircraft currently conduct regular patrols in the East China Sea but the US would like Japan to expand its surveillance flights towards the Spratly Islands.
"I think that JSDF (Japan Maritime Self Defense Forces) operations in the South China Sea makes sense in the future," Admiral Robert Thomas, the top US Navy officer in Asia, told Reuters.
China and Japan are currently in the midst of their own maritime disputes over the Senkaku Islands. China has also begun the construction of an island military base close to the disputed territory.