As for how the Chinese get their spies, Wen Ho Lee was in the U.S. for years, then went to work in Los Alamos in 1978. A few years later, the Chicoms came knocking, and they weren't at all shy about what they wanted. From Wiki:
An investigation of Lee found that he had been invited to China to speak with scientists on two occasions in the 1980s. During the investigation, and after being confronted with questions about his actions and behavior, Lee reported that he had been approached ten years earlier on his second visit to China by two scientists who requested that he assist them and China with the development of nuclear missiles.
Wen Ho Lee was Chinese. The Chinese reptile masters knew they could trust him not to rat out their approach to U.S. security people like Notra Trulock, who was the person to whom he should have gone immediately.
Notra Turlock used to be a freeper, wonder if he’s still around. Interesting man.