The moment when two members of a spy network smuggling the United States' sensitive military secrets to China were apprehended by the FBI just as they were about to board a plane.Tai Wang Mak and his wife Fuk Heung Li were preparing for a flight to China. In their luggage, however, was an encrypted CD.The CD contained information on sensitive technologies developed by the U.S. Navy for its submarines and warships.Leading the list was a technology called Quiet Electric Drive, an electric propulsion system designed to reduce the noise produced by submarines and warships, thereby making detection more difficult. At the center of the file was the name of Tai Mak's older brother, Chi Mak.Chi Mak, an engineer at Power Paragon in California, had access to systems developed for the U.S. Navy. He would take the technical information home, copy it onto CDs, and hand it over to his brother Tai Mak.Tai Mak, in turn, was the courier who encrypted this information and transported it to China.In the FBI's investigation, shredded documents were also recovered from the trash at Chi Mak's home. The documents contained instructions from Chinese intelligence on intelligence gathering and lists of military technologies to be researched.The targets were not limited to submarine propulsion systems alone.Various technologies related to torpedoes, aircraft carrier electronic systems, electromagnetic launch technologies, next-generation warships, and nuclear submarines were also on the intelligence-gathering list. The FBI's investigation lasted about a year. The spy network's activities were monitored through cameras installed in the home, covert searches, electronic surveillance, and communication records. And the operation's critical moment arrived on the night of October 28, 2005.While the FBI raided Chi Mak's home, Tai Mak and his wife were taken into custody at Los Angeles International Airport just before boarding the flight to China.The encrypted CD was also retrieved from their luggage.Chi Mak was later convicted of charges related to transferring military technologies to Chinese intelligence and sentenced to 24 years in prison in 2008. Other family members also pleaded guilty in the case. This file, too, took its place in history as one of the notable examples of China's intelligence activities targeting American military secrets.