Recent visitors to the bay surrounding a submarine base on the southern coast of China's Hainan Island describe a curious nocturnal phenomenon. Powerful spotlights are sometimes trained directly on the ocean frontages of neighboring hotels at night, making visibility out to sea virtually impossible. Some of the lights are mounted on land and others on passing naval patrol boats.
"The effect is incredible," said one recent visitor. "The glare is so great you can hardly stand it on the balcony. You go inside and draw the curtains tight."
The blinding lights cannot obscure something of intense interest to the world's military intelligence agencies: evidence that China has made a breakthrough in its drive to rival America and Russia as a nuclear arms power.