There’s a lot of noise online about “going to DEFCON 1.” Here’s a clear, sourced explainer—what each level is, who sets it, how it’s used across the force, real historical examples, and how it differs from other alert systems and exercise jargon.
Quick myths vs. facts
- DEFCON counts down, not up. 5 is normal; 1 is maximum readiness. [1]
- It’s not a single nationwide dial. Different commands (and sometimes specific forces) can be at different DEFCONs. [2][3]
- The current DEFCON isn’t public. DoD does not routinely announce it. Beware “current DEFCON” websites—they’re not official. [4][5]
- Exercises use codewords (e.g., “ROUND HOUSE”) so practice traffic isn’t mistaken for the real thing. [6]
What DEFCON is—and who sets it
DEFCON (Defense Readiness Condition) is a graduated set of five alert postures used by the U.S. Armed Forces. It was created by the Joint Chiefs of Staff (JCS) in 1959 to give commanders uniform, stepwise guidance during crises. [7]
In practice, the President and Secretary of Defense control DEFCON through the Chairman of the Joint Chiefs of Staff (CJCS) and the combatant commanders. Orders flow via the National Military Command Center (NMCC) and other command-and-control channels. The detailed playbook for alerts has a classified lineage (e.g., the CJCS “Alert System” manuals), which is why public descriptions are necessarily general. [8][9]
Important: The U.S. does not routinely publish a current DEFCON to the public. If you see a site claiming the official nationwide DEFCON today, that’s an independent estimate, not a DoD release. [10]
The five DEFCON levels (with exercise codewords)
| Level | Exercise term | Plain-English meaning | Typical posture cues (illustrative) |
| DEFCON 5 | FADE OUT | Lowest state of readiness; routine ops | Normal day-to-day posture. [11][12] |
| DEFCON 4 | DOUBLE TAKE | Above normal; increased intel watch and tightened security | Heavier indications & warning (I&W), security measures elevated. [13] |
| DEFCON 3 | ROUND HOUSE | Significant increase in readiness | Portions of forces on higher alert; leaves curtailed; air units poised to generate quickly (historically, USAF ready to mobilize in ~15 minutes). [14][15] |
| DEFCON 2 | FAST PACE | One step from maximum readiness | Forces poised for combat, deployments accelerated; nuclear forces at near-launch posture in some eras/commands. [16][17] |
| DEFCON 1 | COCKED PISTOL | Maximum readiness | War plans executable immediately; highest alert. (The U.S. has not publicly acknowledged reaching DEFCON 1.) [18][19] |
Why codewords? In exercises, using “ROUND HOUSE” instead of “DEFCON 3” reduces the chance that simulated messages are confused with real-world orders. [20]
How a DEFCON is used in the real world
DEFCON is scalable. The CJCS may direct specific commands or mission sets to adopt a tighter posture while others remain lower. Two canonical examples:
- Cuban Missile Crisis (1962): Most U.S. forces were placed at DEFCON 3; Strategic Air Command (SAC) alone went to DEFCON 2, dispersing bombers/tankers and sustaining a high airborne alert. [21][22]
- Yom Kippur War (1973): U.S. forces worldwide went to DEFCON 3 as a signal amid risk of superpower escalation. [23]
- September 11, 2001: The Pentagon directed DEFCON 3 (with a standby to consider DEFCON 2); it was later lowered. [24][25]
These show that different forces can sit at different DEFCONs, depending on mission and theater. [26]
What could trigger a change?
Exact thresholds are classified and context-dependent, but historically, indicators and warnings that can drive a shift include:
- Hard intelligence of imminent attack or major adversary mobilization
- Strategic force movements (e.g., ballistic missile activity)
- Collisions of great-power forces in crisis zones
- Attacks on the U.S. homeland or treaty allies
During the 1973 alert, for instance, DEFCON 3 accompanied concern over possible Soviet movements toward the Middle East. During 9/11, it reflected a rapid homeland defense posture. [27][28]
What the military actually does at each level (typical measures)
Below are examples (not a complete or universal checklist); actions vary by command and the nature of the crisis:
- DEFCON 4 → 3: Heightened I&W; recall key personnel; cancel non-essential leave; posture selected air and naval assets for quick generation; disperse aircraft; increase airborne early warning/CAP; tighten base security; raise comms readiness. (SAC’s 1973 measures included bomber/tanker dispersal and expanded airborne alert.) [29]
- DEFCON 3 → 2: Surge sortie generation; accelerate deployment timelines; loadouts adjusted; nuclear forces go to near-maximum readiness in commands directed to do so; elevated alert crews and command posts. (SAC at DEFCON 2 during 1962 is the classic example.) [30]
- DEFCON 2 → 1: Final war-execution posture—commands are ready to carry out war plans on order. (Descriptions exist in declassified Emergency Action Procedures; specifics remain tightly controlled.) [31]
National vs. regional vs. service specifics
- Not all at once, not all the same. DEFCON is an alert framework applied by unified combatant commands. Different commands, or even specific forces within a command, may be ordered to different DEFCONs based on mission. [32]
- Services don’t own separate “DEFCONs.” The Army, Navy, Air Force, Marine Corps, and Space Force execute DEFCON directives through their components, but each service also has its own readiness terms for internal unit posture (see below). [33]
Don’t confuse DEFCON with these other systems
- FPCON (Force Protection Condition): Base/installation security posture against terrorism (NORMAL/ALPHA/BRAVO/CHARLIE/DELTA). This is about gates, guards, and protective measures—not nuclear or strategic readiness. [34]
- REDCON (Army unit readiness condition): A tactical unit’s immediate readiness to move and fight (REDCON-1 to -4). [35]
- INFOCON / CYBERCON: Information/cyber defense postures used by DoD and U.S. Cyber Command. [36]
- WATCHCON (Korean theater): Reconnaissance/surveillance posture on the Korean Peninsula—often confused online with DEFCON. [37]
- LERTCON / EMERGCON: The broader family of alert conditions; DEFCONs are the five “defense conditions” under LERTCON, while EMERGCONs (e.g., Air Defense Emergency) address immediate air/missile attack. [38][39]
Exercise traffic vs. the real thing
Military exercises generate copious command messages. To avoid false alarms:
- Exercise codewords substitute for DEFCON numbers (e.g., ROUND HOUSE for DEFCON 3; HOT BOX/BIG NOISE for emergency states). [40]
- DoD also runs OPREP-3 “WHITE PINNACLE” drills—unclassified time-standard exercises to ensure commands can rapidly report major incidents to the NMCC. (They’re exercises, not real alerts.) [41]
If you see exercise terms, that’s a strong indicator you’re looking at practice traffic, not an operational alert.
Historical highlights (for context, not prediction)
- 1962: SAC at DEFCON 2 during the Cuban Missile Crisis; most other forces at DEFCON 3. [42]
- 1973: Global DEFCON 3 during the Yom Kippur War. [43]
- 2001: DEFCON 3 during the 9/11 attacks; later lowered to 4. [44]
FAQ
Is DEFCON 1 equal to “nuclear war has started”?
No. It’s maximum readiness, often associated with imminent or ongoing war in classic definitions, but it is about posture, not necessarily that weapons have already launched. [45]
Will the public be told if the U.S. changes DEFCON?
Not as a rule. Historic cases become public later via declassification or official memoirs. Real-time disclosure is rare. [46]
Do DEFCON levels control civilian guidance (like DHS alerts)?
No. Civilian threat advisories (e.g., DHS’s NTAS) are separate from military alert postures.
Why do some websites post a “current DEFCON”?
Because DoD doesn’t publish it, third parties guess from open sources. Treat those as unofficial. [47]
Bottom line
DEFCON is a flexible, command-driven readiness framework—not a single red lever. It can be applied differently across theaters and mission sets, it’s not publicly broadcast, and it must be distinguished from FPCON/REDCON/INFOCON/WATCHCON and from exercise codewords that keep training realistic without causing panic. Understanding those boundaries is the antidote to the internet’s knee-jerk “DEFCON 1!” every time the news turns grim. [48][49][50][51]
Sources & further reading
- National Security Archive, Alerts, Crises, and DEFCONs (JCS origin; command-level application). [52]
- Foreign Relations of the U.S. (FRUS), 1958–60: NSC discussion on the newly established DEFCON system. [53]
- FAS: DEFCON – DEFense CONdition (definitions; LERTCON/EMERGCON context). [54]
- Archive.org (declassified Emergency Action Procedures of the JCS: exercise terms list). [55]
- DoD/USAF manuals on OPREP-3 (including WHITE PINNACLE exercise reporting). [56][57]
- Historical cases: Cuban Missile Crisis (SAC DEFCON 2); Yom Kippur War (global DEFCON 3); 9/11 (DEFCON 3). [58][59][60]
Publisher’s note (for clarity): The DEFCON Warning System is an independent, civilian project and is not affiliated with or endorsed by the U.S. Department of Defense or any U.S. government agency. Its assessments are analytical products and not official DEFCON levels.
