China's creation of artificial islands in the South China Sea is happening so fast that Beijing will be able to extend the range of its navy, air force, coast guard and fishing fleets before long, much to the alarm of rival claimants to the contested waters.

Reclamation work is well advanced on six reefs in the Spratly archipelago, according to recently published satellite photographs and Philippine officials. In addition, Manila said this month that Chinese dredgers had started reclaiming a seventh.

While the new islands won't overturn U.S. military superiority in the region, Chinese workers are building ports and fuel storage depots as well as possibly two airstrips that experts said would allow Beijing to project power deep into the maritime heart of Southeast Asia.