I have a short piece about the military significance of China’s SCS formations at the National Interest:
China has built some islands in the South China Sea. Can it protect them?
During World War II Japan found that control of islands offered some strategic advantages, but not enough to force the United States to reduce each island individually. Moreover, over time the islands became a strategic liability, as Japan struggled to keep them supplied with food, fuel and equipment. The islands of the SCS are conveniently located for China, but do they really represent an asset to China’s military? The answer is yes, but in an actual conflict the value would dwindle quickly.