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DEFCON levels

The defense readiness condition (DEFCON) is an alert state used by the United States Armed Forces.[1][2] For security reasons, the US military does not announce a DEFCON level to the public.[1]

The DEFCON system was developed by the Joint Chiefs of Staff (JCS) and unified and specified combatant commands.[3] It prescribes five graduated levels of readiness (or states of alert) for the U.S. military. It increases in severity from DEFCON 5 (least severe) to DEFCON 1 (most severe) to match varying military situations, with DEFCON 1 signaling the impending outbreak of nuclear warfare.[1][2]

DEFCONs are a subsystem of a series of "Alert Conditions", or LERTCONs, which also include Emergency Conditions (EMERGCONs).[4]


The DEFCON level is controlled primarily by the U.S. president and the U.S. Secretary of Defense through the Chairman of the Joint Chiefs of Staff and the Combatant Commanders; each level defines specific security, activation and response scenarios for the personnel in question.[1]

Different branches of the U.S. Armed Forces (i.e. U.S. Army, U.S. Navy, U.S. Air Force, U.S. Marine Corps, U.S. Coast Guard, U.S. Space Force) and different bases or command groups can be activated at different defense conditions. According to Air & Space/Smithsonian, as of 2022, the U.S. DEFCON level has never been more severe than DEFCON 3. The DEFCON 2 levels in the 1962 Cuban Missile Crisis and 1991 Gulf War applied only to the U.S. Strategic Air Command (SAC).

DEFCONs should not be confused with similar systems used by the US military, such as Force Protection Conditions (FPCONS), Readiness Conditions (REDCONS), Information Operations Condition (INFOCON) and its future replacement Cyber Operations Condition (CYBERCON),[5] and Watch Conditions (WATCHCONS), or the former Homeland Security Advisory System used by the U.S. Department of Homeland Security.

Although a higher DEFCON number refers to a more relaxed defence posture, the term has been misused in popular culture in which "DEFCON 5" is incorrectly used to describe an active conflict situation (such as in the title of the video game Defcon 5), or more figuratively, to describe an aggravated state of mind ("going to DEFCON five"). [1]


Defense readiness conditions vary between many commands and have changed over time,[3] and the United States Department of Defense uses exercise terms when referring to the DEFCON levels during exercises.[1][6] This is to preclude the possibility of confusing exercise commands with actual operational commands.[1][6]

Readiness condition Exercise term Description Readiness
DEFCON 1 COCKED PISTOL Nuclear war is imminent or has already begun Maximum readiness. Immediate response.
DEFCON 2 FAST PACE Next step to nuclear war Armed forces ready to deploy and engage in less than six hours
DEFCON 3 ROUND HOUSE Increase in force readiness above that required for normal readiness Air Force ready to mobilize in 15 minutes
DEFCON 4 DOUBLE TAKE Increased intelligence watch and strengthened security measures Above normal readiness
DEFCON 5 FADE OUT Lowest state of readiness Normal readiness

On January 12, 1966, NORAD "proposed the adoption of the readiness conditions of the JCS system", and information about the levels was declassified in 2006:[7]


After NORAD was created, the command used different readiness levels (Normal, Increased, Maximum) subdivided into eight conditions, e.g., the "Maximum Readiness" level had two conditions "Air Defense Readiness" and "Air Defense Emergency".[7] In October 1959, the JCS Chairman informed NORAD "that Canada and the U.S. had signed an agreement on increasing the operational readiness of NORAD forces during periods of international tension."[7] After the agreement became effective on October 2, 1959,[7] the JCS defined a system with DEFCONs in November 1959 for the military commands.[3] The initial DEFCON system had "Alpha" and "Bravo" conditions (under DEFCON 3) and Charlie/Delta under DEFCON 4, plus an "Emergency" level higher than DEFCON 1 with two conditions: "Defense Emergency" and the highest, "Air Defense Emergency" ("Hot Box" and "Big Noise" for exercises).[7]

The United States has never declared a readiness condition of DEFCON 1 to prepare for nuclear war.[1]

Instances of DEFCON 2 or 3[edit]

DEFCON 2[edit]

Cuban Missile Crisis[edit]

During the Cuban Missile Crisis on October 16–28, 1962, the U.S. Armed Forces (with the exception of United States Army Europe (USAREUR)) were ordered to DEFCON 3. On October 24, Strategic Air Command (SAC) was ordered to DEFCON 2, while the rest of the U.S. Armed Forces remained at DEFCON 3. SAC remained at DEFCON 2 until November 15.[1][8][9] While at DEFCON 2, 92.5% of SAC's weapons systems (approx. 1,479 strike aircraft; 182 Atlas, Titan, and Minuteman missiles; 2,962 total nuclear weapons; and 1,003 refueling tankers) were ready to launch within one hour, while its airborne alert program expanded to include 1/8th of SAC's bomber forces, allowing an average of 65 planes in the air in position to be directed at targets in the Soviet Union at any given time.[10]

DEFCON 3[edit]

Yom Kippur War[edit]

On October 6, 1973, Egypt and Syria launched a joint attack on Israel resulting in the Yom Kippur War. The United States became concerned that the Soviet Union might intervene, and on October 25, US forces, including Strategic Air Command, Continental Air Defense Command, European Command and the Sixth Fleet, were placed at DEFCON 3.[1]

According to documents declassified in 2016, the move to DEFCON 3 was motivated by CIA reports indicating that the Soviet Union had sent a ship to Egypt carrying nuclear weapons along with two other amphibious vessels.[11] Soviet troops never landed and the declassified documents did not disclose the fate of the ship and its cargo.

Over the following days, the various forces reverted to normal status with the Sixth Fleet standing down on November 17.[12]

Operation Paul Bunyan[edit]

Following the axe murder incident at Panmunjom on August 18, 1976, readiness levels for US forces in South Korea were increased to DEFCON 3, where they remained throughout Operation Paul Bunyan.[13]

September 11 attacks[edit]

During the September 11 attacks, Secretary of Defense Donald Rumsfeld ordered the DEFCON level be increased to 3, and also a stand-by for a possible increase to DEFCON 2.[1] It was lowered to DEFCON 4 on September 14.[14]

See also[edit]



  1. ^ a b c d e f g h i j k Tiffini Theisen (2023). "What is DEFCON?". Retrieved 19 November 2023.
  2. ^ a b "Department of Defense Dictionary of Military and Associated Terms" (PDF). 12 April 2001 (As Amended Through 19 August 2009). Archived from the original (PDF) on 8 November 2009. Retrieved 1 February 2014.{{cite web}}: CS1 maint: others (link)
  3. ^ a b c Sagan, Scott D. (Summer 1985). "Nuclear Alerts and Crisis Management" (PDF). International Security. 9 (4): 99–139. doi:10.2307/2538543. JSTOR 2538543. S2CID 154595250. Archived (PDF) from the original on 2016-03-04. Retrieved 2013-05-04 – via Project MUSE.
  4. ^ "Emergency Action Plan (SEAP)" (PDF). United States Army Corps of Engineers Savannah District (CESAS) Plan 500-1-12. 1 August 2001. Archived from the original (PDF) on 2013-02-03.
  5. ^ "Chairman of the Joint Chiefs of Staff Instruction 6510.01F". Archived from the original on 2022-08-09. Retrieved 2017-05-04.
  6. ^ a b "Emergency Action Procedures of the Joint Chiefs of Staff, Volume I - General" (PDF). US DoD FOIA Reading Room. April 24, 1981. pp. 4–7. Archived from the original (PDF) on January 13, 2014.
  7. ^ a b c d e NORAD/CONAD Historical Summary: July -December 1959 (PDF) (Report). Archived (PDF) from the original on 2013-09-27. Retrieved 2013-09-25.
  8. ^ "DEFCON DEFense CONdition". Archived from the original on 2019-06-28. Retrieved 2016-03-06.
  9. ^ Norris, Robert S. (October 24, 2012). "The Cuban Missile Crisis: A Nuclear Order of Battle October/November 1962" (PDF). Wilson Center. Archived (PDF) from the original on October 20, 2018. Retrieved February 8, 2022.
  10. ^ Strategic Air Command (1963). "Strategic Air Command Operations in the Cuban Crisis of 1962 (Historical Study No. 90 Vol. 1)" (PDF). US Strategic Air Command, via the National Security Archive. pp. 58, 66, 97.
  11. ^ Naftali, Tim (26 August 2016). "CIA reveals its secret briefings to Presidents Nixon and Ford". CNN. Archived from the original on 27 August 2016. Retrieved 26 August 2016.
  12. ^ Goldman, Jan (16 June 2011). Words of Intelligence: An Intelligence Professional's Lexicon for Domestic and Foreign Threats. Scarecrow Press. pp. 93–. ISBN 978-0-8108-7476-3. Archived from the original on 18 November 2015. Retrieved 6 March 2016.
  13. ^ Probst, Reed R. (16 May 1977). "Negotiating With the North Koreans: The U.S. Experience at Panmunjom" (PDF). Carlisle Barracks, Pennsylvania: U.S. Army War College. Archived from the original (PDF) on October 24, 2005. Retrieved 17 December 2009.
  14. ^ "Complete 911 Timeline: Donald Rumsfeld's Actions on 9/11". Archived from the original on 2021-07-01. Retrieved 2016-08-02.

External links[edit]

  • Media related to DEFCON at Wikimedia Commons