CIA code names, formally called cryptonyms, are built from a two-letter prefix that identifies a country, region, or internal division, followed by an arbitrary dictionary word chosen precisely because it means nothing. Written as a single uppercase string like MKULTRA or JMWAVE, and occasionally split by a slash in older files (ZR/RIFLE), each name is designed so that anyone who intercepts it learns nothing about what it refers to. Almost everything the public knows about the system comes from documents declassified decades after the operations ended.
How a CIA Cryptonym Is Built
The two-letter prefix is called a digraph. It sits at the front of every cryptonym and quietly encodes the geographic or organizational category the operation belongs to. Everything after it is a random word, and the randomness is the entire point.
If you see AMTRUNK, AMLASH, and AMWORLD in the same set of cables, and you happen to know that AM stands for Cuba, you can infer all three involve Cuban operations. The words “trunk,” “lash,” and “world” still tell you nothing about what any of them actually do. Sometimes the digraph and the word combine into something that looks like a real English term (AEROPLANE), but that’s coincidence rather than design.
A declassified CIA document titled “Assignment of Cryptonyms” describes how identities and cryptonyms were linked by matching numbers on separate lists, physically kept apart so that possessing one list alone revealed nothing. That separation between the name and its meaning is what turns an ordinary label into a security tool.
Why the CIA Bothers With Coded Names
The reason comes down to compartmentalization. Intelligence work generates enormous volumes of sensitive information, and the damage from a leak depends on how much a single document reveals. A cable mentioning “AEROPLANE” is nearly useless to anyone who doesn’t hold the separate, tightly held list linking that cryptonym to its real-world referent.
This mirrors the “need-to-know” principle running through all classified handling. Executive Order 13526, which establishes the current framework for national security classification, restricts access to classified information to people who have both the right clearance and a demonstrated need for the material in their work.1Obama White House Archives. Executive Order 13526 – Classified National Security Information Cryptonyms enforce that boundary in practice. An analyst may hold Top Secret clearance and still have no idea what a cryptonym from another program refers to, because the identity behind it lives in a different compartment.
What the Known Digraphs Stand For
No official master list of CIA digraph assignments has ever been publicly released. What exists in academic and journalistic sources is a reconstruction, built by researchers who cross-referenced thousands of declassified cables and matched cryptonyms to the operations and countries they appeared alongside. Some digraphs were reassigned over time; the Soviet Union alone had its prefix changed at least twice across different eras.
Some of the better-documented assignments:
- AE: Soviet Union (one of several digraphs used across different periods)
- AM: Cuba (1960s era)
- GT: Soviet Union (another period)
- JM: Cuba (used alongside AM for certain operational categories)
- MK: CIA Technical Services Division (1950s–1960s)
- MH: Worldwide operations
- PB: Guatemala
- ST: Tibet (1950–1972)
- SD: Iran
- SM: United Kingdom
- WI: Democratic Republic of the Congo (1960s)
- ZR: Intelligence intercept programs connected to the NSA
- LN: United States
Multiple digraphs sometimes covered the same country because different categories of operations were kept separate. Cuba carried both AM and JM, with JMWAVE identifying the CIA’s Miami station that coordinated anti-Castro activity during the 1960s.
Cryptonyms You’ve Probably Heard Of
MKULTRA
MKULTRA is the most publicly recognized CIA cryptonym. The MK digraph marked it as a project of the Technical Services Division. It was established in April 1953 as a successor to an earlier program called MKDELTA and explored various methods of influencing human behavior, with drugs being one component among several.2Department of Defense. Memorandum for the Secretary of Defense – Experimentation Programs Conducted by the Department of Defense That Had CIA Sponsorship or Participation It ran into the late 1960s and became the subject of a 1977 Senate hearing after most of its files had been destroyed on the order of CIA Director Richard Helms in 1973.3United States Senate. Joint Hearing on Project MKULTRA, the CIAs Program of Research in Behavioral Modification
MHCHAOS
The MH digraph designated worldwide operations. MHCHAOS began on August 15, 1967, under presidential direction, tasked with investigating whether hostile foreign governments were funding or directing American antiwar protesters.4Central Intelligence Agency. Studies in Intelligence Vol. 68, No. 2 – Evolution of Surveillance Policy Housed within the Counterintelligence Staff’s Special Operations Group, it expanded to include overseas collection on the foreign contacts of radical groups along with some domestic operations targeting American citizens.5Gerald R. Ford Presidential Library and Museum. Chapter 11 Special Operations Group – Operation CHAOS The program became public in 1974 and figured prominently in the congressional investigations of CIA domestic activity that followed.
PBSUCCESS
PB stood for Guatemala, and PBSUCCESS was the cryptonym for the CIA-backed overthrow of Guatemalan President Jacobo Árbenz in 1954. President Eisenhower authorized it in August 1953 with a $2.7 million budget covering psychological warfare, political action, and subversion.6National Security Archive. CIA and Assassinations: The Guatemala 1954 Documents The State Department’s published volume on Guatemala from that period includes its own glossary of cryptonyms used in the operation’s cable traffic.7U.S. Department of State. Foreign Relations of the United States 1952-1954 Guatemala – Abbreviations and Cryptonyms
A Note on Operation Mongoose
“Mongoose” is often mentioned alongside these cryptonyms, but it doesn’t follow the digraph system. It was a nickname for the broader covert campaign against Cuba launched in November 1961 after the Bay of Pigs failure, and the individual sub-operations inside it would have carried their own AM or JM cryptonyms.8Office of the Historian. The Bay of Pigs Invasion and Its Aftermath, April 1961 – October 1962
How Military Operation Names Differ
Military operation names get conflated with CIA cryptonyms constantly, and they shouldn’t be. The Department of Defense uses a separate system called NICKA (Nickname, Exercise Term, and Code Word System) that works on different principles.
Under NICKA, a code word is a single classified word attached to real military plans, drawn automatically from pre-allocated blocks. A nickname is unclassified and must be two separate words, with the first word coming from an alphabetical range assigned to a specific military branch or command and the second chosen by planners subject to content limits.9Department of Defense. Chairman of the Joint Chiefs of Staff Manual 3150.29E That’s why “Desert Storm” and “Enduring Freedom” are two-word names.
The critical difference: military nicknames are explicitly unclassified, along with their meaning and the link between the two. CIA cryptonyms work in the opposite direction, treating the connection between the name and its referent as classified. A military nickname is a public label for convenience. A cryptonym is a barrier built to keep something hidden.
The Legal Weight Behind a Cryptonym
The classified status of these names carries real criminal exposure. Under 18 U.S.C. § 798, knowingly disclosing classified information about U.S. codes, ciphers, cryptographic systems, or communication intelligence activities to an unauthorized person carries up to ten years in federal prison, along with fines and mandatory forfeiture of any property derived from or used in the violation.10Office of the Law Revision Counsel. 18 USC 798 – Disclosure of Classified Information
Cryptonyms also interact with the intelligence community’s Sensitive Compartmented Information system. SCI compartments sit above the standard Confidential, Secret, and Top Secret classification levels, and the codewords identifying them are themselves classified. Even someone with Top Secret clearance cannot access SCI material without being “read into” the specific compartment first.
How Any of This Became Public
Nearly every cryptonym the public knows reached daylight through the Freedom of Information Act, mandatory declassification review under Executive Order 13526, or congressional investigations that placed formerly classified material into the record. The 1977 Senate MKULTRA hearing examined events that had occurred 12 to 25 years earlier.3United States Senate. Joint Hearing on Project MKULTRA, the CIAs Program of Research in Behavioral Modification The Rockefeller Commission brought MHCHAOS into public view in the mid-1970s.5Gerald R. Ford Presidential Library and Museum. Chapter 11 Special Operations Group – Operation CHAOS The CIA’s FOIA Electronic Reading Room now hosts thousands of declassified documents, and the State Department’s Foreign Relations of the United States series publishes glossaries decoding cryptonyms from historical periods.
What that means for anyone reading a reconstructed list of digraphs: it’s the product of researchers matching cryptonyms to the operations they appeared next to, not a leaked master key. Some digraphs remain unidentified. Others may have been reassigned in ways the public record can’t yet see.