China continues to quietly dig in on disputed islands in the South China Sea, according to recent satellite images analyzed by an American think tank. The new land reclamation and construction initiatives have been military in nature, converting the islands into naval and air bases.

New Chinese facilities have been discovered on Islands such as Tree Island, a tiny island.08 square miles in area in the Paracel Islands group. The archipelago is disputed by China, Taiwan and Vietnam, with some sections also claimed by Malaysia and the Philippines.

Elsewhere, on the Spratly Island group, China has been building runways, leading to accusations that they intend to turn the islands into airbases. Vietnam has also accused China of using their existing facilities for naval and coast guard deployments in the region.

Theof the South China Sea to be their sovereign territory, and have become increasingly willing to assert that claim as their military grows in size and strength. Earlier in October, Chinese President Xi Jinping addressed the 19th Communist Party Congress and praised the "steady progress" of Chinese construction and land reclamation in the disputed sea.

Although the US has no land claims in the South China Sea, US Navy warships are a frequent sight in the region due to the American policy of maintaining freedom of the seas — a pet issue of the United States for over a century — through Freedom of Navigation Operations (FONOPs). The policy dictates that the US will protect the right of states to freely navigate through international waters, which they say include