Key events in the China spying developments: Mid 1980s: China is believed to have obtained critical design information about the W-88 nuclear warhead, one of the most sophisticated warheads in the U.S. arsenal. 1988: China explodes a ``neutron'' bomb, based on U.S. secrets believed to have been stolen earlier in the 1980s. 1995: U.S. intelligence officials learn of the W-88 theft and inform the FBI. Early 1996: FBI begins an investigation at the Los Alamos National Weapons Laboratory in New Mexico and focuses on a scientist suspected of providing nuclear secrets to China. April 1996: Energy Department officials brief Sandy Berger, deputy national security adviser, on security lapses at weapons laboratory and espionage investigation at Los Alamos. July 1997: Berger is briefed again with more detailed information on the security problems. Berger says he briefed the president. February 1998: President Clinton issues a directive calling for tougher counterintelligence and security measures at the labs. July 1998: A special House committee begins investigating U.S. technology transfers to China, a probe that within months turns its focus on espionage. November 1998: The Energy Department begins to make changes in security counterintelligence. March 8, 1999: A Taiwan born scientist at Los Alamos, Wen Ho Lee, is fired for security violations. He had been under investigation since 1996 in connection with the 1980s theft of the W-88 warhead information. Lee has not been charged with a crime. March 19, 1999: Clinton says he is unaware of ``any espionage which occurred by the Chinese against the labs during my presidency.'' April 1999: After learning that Lee had transferred top-secret nuclear computer codes to his unsecured computer, the Energy Department shuts down computer systems at all its weapons labs, because of possible espionage concerns. May 11, 1999: Energy Secretary Bill Richardson announces an overhaul of security and counterintelligence activities at the Energy Department, including creation of a ``security czar.'' May 25, 1999: The House select committee on Chinese technology transfers issues a 700-page report saying that China had obtained nuclear secrets about all U.S. warheads over a 20 year campaign of espionage. -=-=- 