181 weapons laboratories.” The Chinese intelligence service further obtained from private US defense contractors through cyber espionage important elements of the stealth technology used in both advanced planes and submarines. China shared (or exchanged) the fruits of its espionage on nuclear warhead design with North Korea, Pakistan, Iran and Russia. Despite its formidable intelligence coups in the US, the Chinese intelligence service managed to remain among the most elusive of America’s intelligence adversaries. Its espionage organizations are hidden behind layers of bureaucracy in the Ministry of State Security, Chinese Communist party structures, and the second, third and fourth department of the General Staff of the People’s Liberation Army. Much of its cyber espionage units are concealed on the campuses of its universities. Its hierarchy, or order of battle, is also obscure. Few traces have been uncovered of any conventional espionage networks in the United States and no major Chinese spy has ever been arrested. Part of the reason that Chinese espionage has proved so elusive to the eyes of western counter-intelligence, was that, unlike Russia, it did not ordinarily rely on intelligence officers in its embassies to recruit penetration agents to steal secrets. It did not even have an embassy in the United States during most of the Cold War. Instead, its services specialize it assembly mosaics of intelligence assembled from a wide variety of sources including non-classified documents, returning graduate students, scientific conferences, exchanges with allies, and a vast operation of hacking into computers, or cyber- espionage. Cyber-espionage is indeed a vast enterprise in China. Graduating over 150,000 computer science engineers, it had no shortage of personnel. It also had developed the cyber tool kit to gain access to the computer networks of US government contractors and consultants in the private sector and government agencies, planting “sleeper” bugs in