Changbiao in the eastern China Sea was, until recently, an unremarkable and largely uninhabited island.

But rapid construction in recent years has swept away trees and undergrowth to build one of the most sophisticated and closely-guarded government projects: “fast breeder” nuclear reactors.

The territory is now home to the first of two units, which China’s Communist Party says are purely for civilian purposes

Experts and Western officials, however, believe the tiny island could soon become the hub of Beijing’s rapidly-expanding nuclear arsenal.