|“||The progress of science in furnishing the Government with means of espionage is not likely to stop with wire-tapping. Ways may someday be developed by which the Government, without removing papers from secret drawers, can reproduce them in court, and by which it will be enabled to expose to a jury the most intimate occurrences of the home.||”|
|“||1. The act or practice of spying or of using spies to obtain secret intelligence. 2. Overt, covert, or clandestine activity.||”|
|“||(1) Intelligence activity directed toward the acquisition of information through clandestine means and proscribed by the laws of the country against which it is committed; or (2) Overt, covert, or clandestine activity designed to obtain information relating to the national security with intent or reason to believe that it will be used to the injury of the U.S. or to the advantage of a foreign nation.||”|
|“||[t]he act of obtaining, delivering, transmitting, communicating, or receiving information about the national defense with an intent, or reason to believe, that the information may be used to the injury of the United States or to the advantage of any foreign nation.||”|
|“||one nation's attempts to gather intelligence on other nations, where intelligence information includes information related to national security and foreign affairs.||”|
|“||a process that involves human sources or technical means to obtain information that normally is not publicly available.||”|
|“||[a]ctions directed toward the acquisition of information through clandestine operations.||”|
"Espionage has a long history and is nearly always practiced in both directions. For the U.S. and many other states, traditional espionage has been a state-sponsored intelligence-gathering function focused on national security, defense, and foreign policy issues."
- Olmstead v. United States, 277 U.S. 438 (1928) (full-text).
- OPSEC Glossary of Terms.
- Intelligence Community Standard 700-01, at 10.
- U.S. Department of Defense, Joint Pub. 1–02: DOD Dictionary of Military and Associated Terms (Nov. 8, 2010, as amended through May 15, 2011) (full-text).
- At the Nexus of Cybersecurity and Public Policy: Some Basic Concepts and Issues, at 14.
- Threat Landscape and Good Practice Guide for Internet Infrastructure, at 17.
- AR 381-20, at 50.
- Department of Defense Cyberspace Policy Report, at 6.
- Computer espionage
- Computer network exploitation
- Counterespionage Section
- Cyber espionage
- Economic espionage
- Economic Espionage Act of 1996
- Economic Espionage: The Threat to U.S. Industry
- Espionage Act of 1917
- Foreign Spies Stealing US Economic Secrets in Cyberspace
- Industrial espionage
- State-sponsored espionage