RARE VIDEO SHOWS PENTAGON EMPLOYEE SELLING SECRETS TO A CHINESE SPY -- "60 MINUTES"

China's Spies May Now Pose the Biggest Espionage Threat to the U.S.

60 MINUTES has obtained an FBI videotape showing a Defense Department employee selling secrets to a Chinese spy for cash. The video, which has never been made public before, offers a rare glimpse into the secretive world of espionage and illustrates how China's spying may now pose the biggest espionage threat to the U.S. Scott Pelley's report will be broadcast on 60 MINUTES Sunday, Feb. 28 (7:00-8:00 PM, ET/PT) on the CBS Television Network.

China may be the number-one espionage threat now. "The Chinese are the biggest problem we have with respect to the level of effort that they're devoting against us, versus the level of attention we are giving to them," says Michelle Van Cleave, once America's top counter-intelligence officer who coordinated the hunt for foreign spies from 2003 to 2006.

"Definitely, without a doubt," the Chinese focus most of their espionage on the U.S., says Fengzhi Li, who once recruited spies for China's Ministry of State Security and is now in the U.S. seeking asylum.

The Chinese, says Van Cleave, have had the designs to all of the nuclear weapons in the U.S. arsenal for years and they have been after a lot more lately. "Virtually every technology that is on the U.S. control technology list has been targeted at one time or another by the Chinese," she tells Pelley. "Sensors and optics...biological and chemical processes...all the things we have identified as having inherent military application," says Van Cleave. "I think we are a real candy store for the Chinese and for others."

In the videotape obtained by 60 MINUTES, Gregg Bergersen, a civilian Pentagon worker with a high-security clearance, is shown taking money, about $2,000, from the Chinese spy, Tai Shen Kuo. Bergersen then discusses how he will let Kuo look at secret documents. The documents included the types of weapons the U.S. was selling to its ally Taiwan as well as plans for a classified command and control system that was going to be used by Taiwan.

Bergersen clearly implicates himself on the videotape. "I'm very , very, very reticent to let you have it because it's all classified, but I will let you see it," he tells Kuo. "You know you can write all...the notes you want...its just I can never let anyone know...I'd get fired for sure on that," says Bergersen. "Well, not even get fired, I'd go to &%$#ing jail!" Watch an excerpt.

That's where Bergersen is now, serving almost five years in federal prison for communicating national defense information. Kuo, a naturalized American citizen, was given 15 years for espionage. Both men pleaded guilty after being shown the tape and other evidence against them.