Island force keeps 'southern gate' safe

A small group of police officers is charged with ensuring the safety of a collection of outcrops, islands and reefs in the South China Sea. Zhang Zhihao reports from Sansha, Hainan province.

With palm trees, warm breezes and skies as blue as the sea, Sansha - a collection of islands, reefs and areas of ocean in the South China Sea which form China's southernmost prefecture-level city - seems like a tropical paradise.

Appearances can be deceptive, though, and for outsiders trouble and danger can emerge from the most unlikely places, even the water supply.