On a clear night, the Filipinos who live on Pagasa Island — a speck in the vast South China Sea — can see the floodlights from giant Chinese cranes working around the clock, dredging sand to build up a nearby reef.

Life on the atoll with its clutch of buildings was for decades leisurely and quiet, with sporadic Internet access and not much to do but fish and stroll on the beach.

Now its 120-odd residents find themselves on the doorstep of a dispute over territory that has fed tensions among some of the world's biggest powers. Change has come to Pagasa in the constant presence of China.