Confirmed Records · Since 1962
DEFCON Level History
Complete history of defense condition changes documented in confirmed records and declassified sources.
Confirmed Changes Only: This page shows only confirmed DEFCON changes confirmed by the U.S. government. For OSINT-based estimates and recent level changes, visit our Level Changes page.
About the DEFCON System
The DEFCON (DEFense readiness CONdition) system was introduced after NORAD's creation in 1957. Originally more complex with 8 alert conditions across 3 readiness levels, it was later simplified to the 5-level system used today.
The system allows different military commands to be at different DEFCON levels simultaneously. For example, during the Cuban Missile Crisis, Strategic Air Command (SAC) was at DEFCON 2 while other commands remained at different levels.
Important Note: Confirmed DEFCON changes are classified and often not confirmed until years later for security reasons. The levels shown on this website are OSINT estimates based on open-source intelligence analysis, not government classifications.
How DEFCON Levels Are Determined
DEFCON levels are set by the Joint Chiefs of Staff and the President based on:
- Intelligence assessments of global threats
- Military readiness requirements
- Geopolitical tensions and conflicts
- Nuclear and strategic weapon threats
- Cyber attacks on critical infrastructure
- Terrorist threats and security concerns
Confirmed DEFCON Changes
View OSINT Changes →2000s
September 11 Attacks
1990s
Gulf War - Operation Desert Storm
1970s
Operation Paul Bunyan
Yom Kippur War
1960s
Cuban Missile Crisis
How DEFCON Levels Are Determined - Source: www.defconlevel.com/history