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The defense readiness condition (DEFCON) is an
alert state An alert state or state of alert is an indication of the state of readiness of the armed forces for military action or a state against natural disasters, terrorism or military attack. The term frequently used is "on high alert". Examples scales ...
used by the
United States Armed Forces The United States Armed Forces are the military forces of the United States. The armed forces consists of six service branches: the Army, Marine Corps, Navy, Air Force, Space Force, and Coast Guard. The president of the United States is ...
. (DEFCON is not mentioned in the 2010 and newer document) The DEFCON system was developed by the
Joint Chiefs of Staff The Joint Chiefs of Staff (JCS) is the body of the most senior uniformed leaders within the United States Department of Defense, that advises the president of the United States, the secretary of defense, the Homeland Security Council and the ...
(JCS) and unified and specified combatant commands. 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 signalling the outbreak of
nuclear warfare Nuclear warfare, also known as atomic warfare, is a theoretical military conflict or prepared political strategy that deploys nuclear weaponry. Nuclear weapons are weapons of mass destruction; in contrast to conventional warfare, nuclear ...
. DEFCONs are a subsystem of a series of Alert Conditions, or
LERTCON In United States military doctrine, LERTCON is an abbreviation of alert condition, and is a measure of the level of action and readiness to be taken in a given situation. LERTCON is used by US and Allied forces who are assigned to NATO. There are s ...
s, which also include Emergency Conditions (EMERGCONs).


Definition

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 The chairman of the Joint Chiefs of Staff (CJCS) is the presiding officer of the United States Joint Chiefs of Staff (JCS). The chairman is the highest-ranking and most senior military officer in the United States Armed Forces Chairman: app ...
and the Combatant Commanders; each level defines specific security, activation and response scenarios for the personnel in question. Different branches of the U.S. Armed Forces (i.e. U.S. Army, U.S. Navy, U.S. Air Force,
U.S. Marine Corps The United States Marine Corps (USMC), also referred to as the United States Marines, is the maritime land force service branch of the United States Armed Forces responsible for conducting expeditionary and amphibious operations through co ...
, U.S. Coast Guard,
U.S. Space Force The United States Space Force (USSF) is the space service branch of the U.S. Armed Forces, one of the eight U.S. uniformed services, and the world's only independent space force. Along with its sister branch, the U.S. Air Force, the Space ...
) and different bases or command groups can be activated at different defense conditions. According to '' Air & Space/Smithsonian'', , the U.S. DEFCON level has never been more severe than DEFCON 3. The DEFCON 2 levels in the 1962
Cuban Missile Crisis The Cuban Missile Crisis, also known as the October Crisis (of 1962) ( es, Crisis de Octubre) in Cuba, the Caribbean Crisis () in Russia, or the Missile Scare, was a 35-day (16 October – 20 November 1962) confrontation between the United S ...
and 1991
Gulf War The Gulf War was a 1990–1991 armed campaign waged by a 35-country military coalition in response to the Iraqi invasion of Kuwait. Spearheaded by the United States, the coalition's efforts against Iraq were carried out in two key phases: ...
applied only to the U.S. DEFCONs should not be confused with similar systems used by the U.S. military, such as
Force Protection Condition In United States military security parlance, force protection condition (FPCON for short) is a counter- terrorist threat system overseen by the United States Department of Defense directive, and describes the number of measures needed to be take ...
s (FPCONS), Readiness Conditions (REDCONS), Information Operations Condition (INFOCON) and its future replacement Cyber Operations Condition (CYBERCON), and Watch Conditions (WATCHCONS), or the former
Homeland Security Advisory System In the United States, the Homeland Security Advisory System (HSAS) was a color-coded terrorism threat advisory scale created in March 2002 under the Bush Administration in response to the September 11 attacks. The different levels triggered ...
used by the U.S. Department of Homeland Security.


Levels

Defense readiness conditions vary between many commands and have changed over time, and the
United States Department of Defense The United States Department of Defense (DoD, USDOD or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government directly related to national sec ...
uses exercise terms when referring to the DEFCON levels during exercises. This is to preclude the possibility of confusing exercise commands with actual operational commands. On January 12, 1966,
NORAD North American Aerospace Defense Command (NORAD ), known until March 1981 as the North American Air Defense Command, is a combined organization of the United States and Canada that provides aerospace warning, air sovereignty, and protection ...
"proposed the adoption of the readiness conditions of the JCS system", and information about the levels was declassified in 2006:


History

After
NORAD North American Aerospace Defense Command (NORAD ), known until March 1981 as the North American Air Defense Command, is a combined organization of the United States and Canada that provides aerospace warning, air sovereignty, and protection ...
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". 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." After the agreement became effective on October 2, 1959, the JCS defined a system with DEFCONs in November 1959 for the military commands. 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).


Instances of DEFCON 2 or 3


DEFCON 2


Cuban Missile Crisis

During the
Cuban Missile Crisis The Cuban Missile Crisis, also known as the October Crisis (of 1962) ( es, Crisis de Octubre) in Cuba, the Caribbean Crisis () in Russia, or the Missile Scare, was a 35-day (16 October – 20 November 1962) confrontation between the United S ...
on October 16–28, 1962, the U.S. Armed Forces (with the exception of
United States Army Europe United States Army Europe and Africa (USAREUR-AF) is an Army Service Component Command (ASCC) /Theater Army responsible for directing United States Army operations throughout the U.S. European Command (EUCOM) and U.S. Africa Command (AFRICO ...
(USAREUR)) were ordered to DEFCON 3. On October 24,
Strategic Air Command Strategic Air Command (SAC) was both a United States Department of Defense Specified Command and a United States Air Force (USAF) Major Command responsible for command and control of the strategic bomber and intercontinental ballistic missile ...
(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.


Persian Gulf War

On January 15, 1991, the
Joint Chiefs of Staff The Joint Chiefs of Staff (JCS) is the body of the most senior uniformed leaders within the United States Department of Defense, that advises the president of the United States, the secretary of defense, the Homeland Security Council and the ...
declared DEFCON 2 in the opening phase of
Operation Desert Storm Operation or Operations may refer to: Arts, entertainment and media * ''Operation'' (game), a battery-operated board game that challenges dexterity * Operation (music), a term used in musical set theory * ''Operations'' (magazine), Multi-Ma ...
during the Persian Gulf War.Meyers, Harold P. (1992)
Nighthawks over Iraq, a study a study of the F117-A stealth fighter in operations Desert Shield and Desert Storm
." U.S. Air Force Office of History.


DEFCON 3


Yom Kippur War

On October 6, 1973, Egypt and Syria launched a joint attack on Israel resulting in the
Yom Kippur War The Yom Kippur War, also known as the Ramadan War, the October War, the 1973 Arab–Israeli War, or the Fourth Arab–Israeli War, was an armed conflict fought from October 6 to 25, 1973 between Israel and a coalition of Arab states led by E ...
. The United States became concerned that the Soviet Union might intervene, and on October 25, US forces, including
Strategic Air Command Strategic Air Command (SAC) was both a United States Department of Defense Specified Command and a United States Air Force (USAF) Major Command responsible for command and control of the strategic bomber and intercontinental ballistic missile ...
, Continental Air Defense Command,
European Command The United States European Command (EUCOM) is one of the eleven unified combatant commands of the United States military, headquartered in Stuttgart, Germany. Its area of focus covers and 51 countries and territories, including Europe, Russ ...
and the Sixth Fleet, were placed at DEFCON 3. According to documents declassified in 2016, the move to DEFCON 3 was motivated by
CIA The Central Intelligence Agency (CIA ), known informally as the Agency and historically as the Company, is a civilian foreign intelligence service of the federal government of the United States, officially tasked with gathering, processing, ...
reports indicating that the Soviet Union had sent a ship to Egypt carrying nuclear weapons along with two other amphibious vessels. 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.


Operation Paul Bunyan

Following the axe murder incident at
Panmunjom Panmunjom, also known as Panmunjeom, now located in Paju, Gyeonggi Province, South Korea or Kaesong, North Hwanghae Province, North Korea, was a village just north of the ''de facto'' border between North and South Korea, where the 1953 Korean A ...
on August 18, 1976, readiness levels for US forces in South Korea were increased to DEFCON 3, where they remained throughout
Operation Paul Bunyan The Korean axe murder incident (, ) was the killing of two US Army officers, Captain Arthur Bonifas and First Lieutenant Mark Barrett, by North Korean soldiers on August 18, 1976, in the Joint Security Area (JSA) in the Korean Demilitarized Z ...
.


September 11 attacks

During the
September 11 attacks The September 11 attacks, commonly known as 9/11, were four coordinated suicide terrorist attacks carried out by al-Qaeda against the United States on Tuesday, September 11, 2001. That morning, nineteen terrorists hijacked four commer ...
, Secretary of Defense
Donald Rumsfeld Donald Henry Rumsfeld (July 9, 1932 – June 29, 2021) was an American politician, government official and businessman who served as Secretary of Defense from 1975 to 1977 under president Gerald Ford, and again from 2001 to 2006 under Preside ...
ordered the DEFCON level be increased to 3, and also a stand-by for a possible increase to DEFCON 2. It was lowered to DEFCON 4 on September 14.


See also

*
COGCON COGCON ("continuity of government readiness condition") is a United States government readiness level, roughly analogous to the DEFCON alert state system, tracking the readiness of the government in the event of an emergency. The system was introdu ...
– Continuity of government readiness level *
Combat readiness readiness is a condition of the armed forces and their constituent units and formations, warships, aircraft, weapon systems or other military technology and equipment to perform during combat military operations, or functions consistent with th ...
*
Doomsday Clock The Doomsday Clock is a symbol that represents the likelihood of a man-made global catastrophe, in the opinion of the members of the ''Bulletin of the Atomic Scientists''. Maintained since 1947, the clock is a metaphor for threats to humanity ...
* HURCON – Hurricane Condition threat rating (military-developed scale) *
National Command Authority (United States) National Command Authority (NCA) is a term that was used by the Department of Defense of the United States of America to refer to the ultimate source of lawful military orders. The NCA was first alluded to in a 1960 Department of Defense document. ...
*
National Military Command Center The National Military Command Center (NMCC) is a Pentagon command and communications center for the National Command Authority (i.e., the President of the United States and the United States Secretary of Defense). Maintained by the Department ...
*
National Terrorism Advisory System The National Terrorism Advisory System (NTAS) is a terrorism threat advisory scale used by the US Department of Homeland Security since April 26, 2011. The NTAS is the replacement for the often-criticized, color-coded Homeland Security Adviso ...
*
UK Threat Levels The United Kingdom Terror Threat Levels, often referred to as UK Threat Levels, are the alert states that have been in use since 1 August 2006 by the British government to warn of forms of terrorist activity. In September 2010 the threat levels ...
– Similar British system used for terrorism threats


References


External links

* {{commons category-inline, DEFCON Alert measurement systems