Able Archer 83 Able Archer 83 was a ten - day NATO command post exercise starting on November 2 , 1983 , that spanned Western Europe , centered on the Supreme Headquarters Allied Powers Europe ( SHAPE ) Headquarters situated at Casteau , north of the Belgian city of Mons . Able Archer exercises simulated a period of conflict escalation , culminating in a coordinated nuclear attack . < br > The 1983 exercise incorporated a new , unique format of coded communication , radio silence s , participation by heads of government , and a simulated DEFCON 1 nuclear alert . The realistic nature of the 1983 exercise , coupled with deteriorating relations between the United States and the Soviet Union and the anticipated arrival of strategic Pershing II nuclear missiles in Europe , led some members of the Soviet Politburo and Soviet military to believe that Able Archer 83 was a ruse of war , obscuring preparations for a genuine nuclear first strike . In response , the Soviets readied their nuclear forces and placed air units in East Germany and Poland on alert . This is known as the 1983 war scare . The 1983 war scare is considered by many historians to be the closest the world has come to nuclear war since the Cuban Missile Crisis of 1962 . The threat of nuclear war ended with the conclusion of the exercise on November 11 . Prelude to NATO exercise . Operation RYAN . The greatest catalyst to the Able Archer war scare occurred more than two years earlier . In a May 1981 closed - session meeting of senior KGB officers and Soviet leaders , General Secretary Leonid Brezhnev and KGB chairman Yuri Andropov bluntly announced that the United States was preparing a secret nuclear attack on the USSR . To combat this threat , Andropov announced , the KGB and GRU would begin Operation RYAN . RYAN ( РЯН ) was a Russian acronym for " Nuclear Missile Attack " ( Ракетное Ядерное Нападение ) ; Operation RYAN was the largest , most comprehensive peacetime intelligence - gathering operation in Soviet history . Agents abroad were charged with monitoring the figures who would decide to launch a nuclear attack , the service and technical personnel who would implement the attack , and the facilities from which the attack would originate . In all probability , the goal of Operation RYAN was to discover the first " intent " of a nuclear attack and then preempt it . The impetus for the implementation of Operation RYAN is still largely unknown . However , the Nazi sneak attack and subsequent invasion on the Soviet Union in 1941 has remained a vital lesson for the Soviet armed forces ever since . Oleg Gordievsky , the highest - ranking KGB official ever to defect , suspected that it was born of the increased " Soviet Paranoia " coupled with " Reaganite Rhetoric " . Gordievsky conjectured that Brezhnev and Andropov , who " were very , very old - fashioned and easily influenced . . . by Communist dogmas " , truly believed that an antagonistic Ronald Reagan would push the nuclear button and relegate the Soviet Union to the literal " ash heap of history " . Central Intelligence Agency historian Benjamin B . Fischer lists several concrete occurrences that likely led to the birth of RYAN . The first of these was the use of psychological operations ( PSYOP ) that began soon after President Reagan took office . PSYOP . Psychological operations by the United States began mid - February 1981 and continued intermittently until 1983 . These included a series of clandestine naval operations that stealthily accessed waters near the Greenland - Iceland - United Kingdom ( GIUK ) gap , and the Barents , Norwegian , Black , and Baltic seas , demonstrating how close NATO ships could get to critical Soviet military bases . American bombers also flew directly towards Soviet airspace , peeling off at the last moment , occasionally several times per week . These near penetrations were designed to test Soviet radar vulnerability as well as demonstrate US capabilities in a nuclear war . " It really got to them , " recalls Dr . William Schneider , [ former ] undersecretary of state for military assistance and technology , who saw classified " after - action reports " that indicated U . S . flight activity . " They didn ' t know what it all meant . A squadron would fly straight at Soviet airspace , and other radars would light up and units would go on alert . Then at the last minute the squadron would peel off and return home . " In April , the United States Navy conducted FleetEx ' 83 , the largest fleet exercise held to date in the North Pacific . The conglomeration of approximately forty ships with 23 , 000 crewmembers and 300 aircraft , was arguably the most powerful naval armada ever assembled . U . S . aircraft and ships attempted to provoke the Soviets into reacting , allowing the U . S . Office of Naval Intelligence to study Soviet radar characteristics , aircraft capabilities , and tactical maneuvers . On April 4 at least six U . S . Navy aircraft flew over Zeleny Island , one of the Kurile Islands . The Soviets were outraged , and ordered a retaliatory overflight of U . S . Aleutian Islands . The Soviet Union also issued a formal diplomatic note of protest , which accused the United States of repeated penetrations of Soviet airspace . Korean Air Lines Flight 007 . On September 1 , 1983 the Korean Air Lines Flight 007 ( KAL 007 ) was shot down over the Sea of Japan near Moneron Island just west of Sakhalin island over prohibited Soviet airspace . All 269 passengers and crew aboard were killed , including Congressman Larry McDonald ( D ) , a sitting member of the United States House of Representatives from Georgia . In conjunction with the extremely secretive PSYOPs against the Soviet Union , the attack brought relations between the two superpowers to a new public low . Illustrating the historically antagonistic relations between the USA and USSR in the early 1980s , the Soviet attack on KAL 007 also lends several insights into Able Archer 83 . Weapons buildup . From the start the Reagan administration adopted an assertive and resolute stance toward the Soviet Union , one that favored matching and exceeding their strategic and global military capabilities . The administration ' s rigorous focus on this objective resulted in the largest peacetime military buildup in the history of the United States . It also ushered in the final major escalation in rhetoric of the Cold War . On June 8 , 1982 , Reagan , in a speech to the British House of Commons confidently declared that , " . . . Freedom and Democracy will leave Marxism and Leninism on the ash heap of history . " On March 23 , 1983 , Reagan announced one of the most ambitious and controversial components to this strategy , the Strategic Defense Initiative ( labeled " Star Wars " by the media and critics ) . While Reagan portrayed the initiative as a safety net against nuclear war , leaders in the Soviet Union viewed it as a definitive departure from the relative weapons parity of détente and an escalation of the arms race into space . Yuri Andropov , who had become General Secretary following Brezhnev ' s death in November 1982 , lambasted Reagan for " inventing new plans on how to unleash a nuclear war in the best way , with the hope of winning it " . Despite the enormous Soviet outcry over the " Star Wars " program , the weapons plan that generated the most alarm among the Soviet Union ' s leadership during Able Archer 83 was the 1979 NATO approval and planned deployment of intermediate - range Pershing II missiles in Western Europe . These missiles , deployed to counter Soviet SS - 20 intermediate - range missiles on its own western border , represented a major threat to the Soviets . The Pershing II was capable of destroying Soviet " hard targets " such as underground missile silo s and command and control bunker s . The missiles could be emplaced and launched from any surveyed site in minutes , and because the guidance system was self - correcting , the missile system possessed a genuine " first strike capability " . Furthermore , it was estimated that the missiles ( deployed in West Germany ) could reach targets in the western Soviet Union within four to six minutes of their launch . These capabilities led Soviet leaders to believe that the only way to survive a Pershing II strike was to preempt it . This fear of an undetected Pershing II attack , according to CIA historian Benjamin B . Fischer , was explicitly linked to the mandate of Operation RYAN : to detect a decision by the United States to launch a nuclear attack and to preempt it . False alarm from the Soviet early missile warning system . On the night of September 26 , 1983 , the Soviet orbital missile early warning system ( SPRN ) , code - named Oko , reported a single intercontinental ballistic missile launch from the territory of the United States . Lieutenant Colonel Stanislav Petrov , who was on duty during the incident , correctly dismissed the warning as a computer error when ground early warning radars did not detect any launches . Part of his reasoning was that the system was new and known to malfunction before ; also , a full - scale nuclear attack from the United States would involve thousands of simultaneous launches , not a single missile . Later , the system reported four more ICBM launches headed to the Soviet Union , but Petrov again dismissed the reports as false . The investigation that followed revealed that the system indeed malfunctioned and false alarms were caused by a rare alignment of sunlight on high - altitude clouds and the satellites ' orbits . Exercise Able Archer 83 . Thus , on November 2 , 1983 , as Soviet intelligence services were attempting to detect the early signs of a nuclear attack , NATO began to simulate one . The exercise , codenamed Able Archer , involved numerous NATO allies and simulated NATO ' s Command , Control , and Communications ( C³ ) procedures during a nuclear war . Some Soviet leaders , because of the preceding world events and the exercise ' s particularly realistic nature , believed — in accordance with Soviet military doctrine — that the exercise may have been a cover for an actual attack . Indeed , a KGB telegram of February 17 described one likely scenario as such : In view of the fact that the measures involved in State Orange [ a nuclear attack within 36 hours ] have to be carried out with the utmost secrecy ( under the guise of maneuvers , training etc ) in the shortest possible time , without disclosing the content of operational plans , it is highly probable that the battle alarm system may be used to prepare a surprise RYAN [ nuclear attack ] in peacetime . The February 17 , 1983 KGB Permanent Operational Assignment assigned its agents to monitor several possible indicators of a nuclear attack . These included actions by " A cadre of people associated with preparing and implementing decision about RYAN , and also a group of people , including service and technical personnel . . . those working in the operating services of installations connected with processing and implementing the decision about RYAN , and communication staff involved in the operation and interaction of these installations . " Because Able Archer 83 simulated an actual release , it is likely that the service and technical personnel mentioned in the memo were active in the exercise . More conspicuously , British Prime Minister Margaret Thatcher and West German Chancellor Helmut Kohl participated ( though not concurrently ) in the nuclear drill . United States President Reagan , Vice President George H . W . Bush , and Secretary of Defense Caspar Weinberger were also intended to participate . Robert McFarlane , who had assumed the position of National Security Advisor just two weeks earlier , realized the implications of such participation early in the exercise ' s planning and rejected it . Another illusory indicator likely noticed by Soviet analysts was an influx of ciphered communications between the United Kingdom and the United States . Soviet intelligence was informed that " so - called nuclear consultations in NATO are probably one of the stages of immediate preparation by the adversary for RYAN " . To the Soviet analysts , this burst of secret communications between the United States and the UK one month before the beginning of Able Archer may have appeared to be this " consultation " . In reality , the burst of communication regarded the US invasion of Grenada on October 25 , 1983 , which caused a great deal of diplomatic traffic as the sovereign of the island was Elizabeth II . A further startling aspect reported by KGB agents regarded the NATO communications used during the exercise . According to the Moscow Centre ' s February 17 , 1983 memo , It [ was ] of the highest importance to keep a watch on the functioning of communications networks and systems since through them information is passed about the adversary ' s intentions and , above all , about his plans to use nuclear weapons and practical implementation of these . In addition , changes in the method of operating communications systems and the level of manning may in themselves indicate the state of preparation for RYAN . Soviet Intelligence appeared to substantiate these suspicions by reporting that NATO was indeed using unique , never - before - seen procedures as well as message formats more sophisticated than previous exercises that possibly indicated the proximity of nuclear attack . Finally , during Able Archer 83 NATO forces simulated a move through all alert phases , from DEFCON 5 to DEFCON 1 . While these phases were simulated , alarmist KGB agents mistakenly reported them as actual . According to Soviet intelligence , NATO doctrine stated , " " Operational readiness No 1 " is declared when there are obvious indications of preparation to begin military operations . It is considered that war is inevitable and may start at any moment . " Upon learning that US nuclear activity mirrored its hypothesized first strike activity , the Moscow Centre sent its residencies a flash telegram on November 8 or 9 ( Oleg Gordievsky cannot recall which ) , incorrectly reporting an alert on American bases and frantically asking for further information regarding an American first strike . The alert precisely coincided with the seven - to ten - day period estimated between NATO ' s preliminary decision and an actual strike . This was the peak of the war scare . The Soviet Union , believing its only chance of surviving a NATO strike was to preempt it , readied its nuclear arsenal . The CIA reported activity in the Baltic Military District , in Czechoslovakia , and it determined that nuclear - capable aircraft in Poland and East Germany were placed " on high alert status with readying of nuclear strike forces " . Former CIA analyst Peter Vincent Pry goes further , saying he suspects that the aircraft were merely the tip of the iceberg . He hypothesizes that — in accordance with Soviet military procedure and history — ICBM silos , easily readied and difficult for the United States to detect , were also prepared for a launch . Soviet fears of the attack ended as the Able Archer exercise finished on November 11 . Upon learning of the Soviet reaction to Able Archer 83 by way of the double agent Oleg Gordievsky , a British SIS asset , President Reagan commented , " I don ' t see how they could believe that — but it ’ s something to think about . " Soviet reaction . The double agent Oleg Gordievsky , whose highest rank was KGB resident in London , is the only Soviet source ever to have published an account of Able Archer 83 . Oleg Kalugin and Yuri Shvets , who were KGB officers in 1983 , have published accounts that acknowledge Operation RYAN , but they do not mention Able Archer 83 . Gordievsky and other Warsaw Pact intelligence agents were extremely skeptical about a NATO first strike , perhaps because of their proximity to , and understanding of , the West . Nevertheless , agents were ordered to report their observations , not their analysis , and this critical flaw in the Soviet intelligence system — coined by Gordievsky as the " intelligence cycle " — fed the fear of US nuclear aggression . According to Vitaly Shlykov , the Soviets started arming their nuclear weapons , and war was only averted because they malfunctioned when the wrong launch codes were entered . Marshal Sergei Akhromeyev , who at the time was Chief of the main operations directorate of the Soviet General Staff , told Cold War historian Don Orbendorfer that he had never heard of Able Archer . The lack of public Soviet response over Able Archer 83 has led some historians , including Fritz W . Ermarth in his piece , " Observations on the ' War Scare ' of 1983 From an Intelligence Perch " , to conclude that Able Archer 83 posed no immediate threat to the Soviet Union . American reaction . In May 1984 , CIA Russian specialist Ethan J . Done drafted " Implications of Recent Soviet Military - Political Activities " , which concluded : " we believe strongly that Soviet actions are not inspired by , and Soviet leaders do not perceive , a genuine danger of imminent conflict with the United States . " Robert Gates , Deputy Director for Intelligence during Able Archer 83 , has published thoughts on the exercise that dispute this conclusion : Information about the peculiar and remarkably skewed frame of mind of the Soviet leaders during those times that has emerged since the collapse of the Soviet Union makes me think there is a good chance — with all of the other events in 1983 — that they really felt a NATO attack was at least possible and that they took a number of measures to enhance their military readiness short of mobilization . After going through the experience at the time , then through the postmortems , and now through the documents , I don ' t think the Soviets were crying wolf . They may not have believed a NATO attack was imminent in November 1983 , but they did seem to believe that the situation was very dangerous . And US intelligence [ SNIE 11 – 9 - 84 and SNIE 11 – 10 – 84 ] had failed to grasp the true extent of their anxiety . A still - classified report written by Nina Stewart for the President ' s Foreign Advisory Board concurs with Gates and refutes the previous CIA reports , concluding that further analysis shows that the Soviets were , in fact , genuinely fearful of US aggression . Some historians , including Beth A . Fischer in her book " The Reagan Reversal " , pin Able Archer 83 as profoundly affecting President Reagan and his turn from a policy of confrontation towards the Soviet Union to a policy of rapprochement . Most other historians say that Reagan always intended to increase the United States defensive ability and then negotiate with the Soviet Union from a position of strength . The thoughts of Reagan and those around him provide important insight upon the nuclear scare and its subsequent ripples . On October 10 , 1983 , just over a month before Able Archer 83 , President Reagan viewed a television film about Lawrence , Kansas being destroyed by a nuclear attack titled " The Day After " . In his diary , the president wrote that the film " left me greatly depressed " . Later in October , Reagan attended a Pentagon briefing on nuclear war . During his first two years in office , he had refused to take part in such briefings , feeling it irrelevant to rehearse a nuclear apocalypse ; finally , he consented to the Pentagon official requests . According to officials present , the briefing " chastened " Reagan . Weinberg said , " [ Reagan ] had a very deep revulsion to the whole idea of nuclear weapons . . . These war games brought home to anybody the fantastically horrible events that would surround such a scenario . " Reagan described the briefing in his own words : " A most sobering experience with < nowiki > [ < / nowiki > Caspar Weinberger < nowiki > ] < / nowiki > and Gen . Vessey in the Situation Room , a briefing on our complete plan in the event of a nuclear attack . " These two glimpses of nuclear war primed Reagan for Able Archer 83 , giving him a very specific picture of what would occur had the situation further developed . After receiving intelligence reports from sources including Gordievsky , it was clear that the Soviets were unnerved . While officials were concerned with the Soviet panic , they were hesitant about believing the proximity of a Soviet attack . Secretary of State George P . Shultz thought it " incredible , at least to us " that the Soviets would believe the US would launch a genuine attack . In general , Reagan did not share the secretary ' s belief that cooler heads would prevail , writing : " We had many contingency plans for responding to a nuclear attack . But everything would happen so fast that I wondered how much planning or reason could be applied in such a crisis . . . Six minutes to decide how to respond to a blip on a radar scope and decide whether to unleash Armageddon ! How could anyone apply reason at a time like that ? " According to McFarlane , the president responded with " genuine anxiety " in disbelief that a regular NATO exercise could have led to an armed attack . To the ailing Politburo — led from the deathbed of the terminally ill Andropov , a man with no firsthand knowledge of the United States , and the creator of Operation RYAN — it seemed " that the United States was preparing to launch . . . a sudden nuclear attack on the Soviet Union " . In his memoirs , Reagan , without specifically mentioning Able Archer 83 , wrote of a 1983 realization : " Three years had taught me something surprising about the Russians : Many people at the top of the Soviet hierarchy were genuinely afraid of America and Americans . Perhaps this shouldn ' t have surprised me , but it did . . . During my first years in Washington , I think many of us in the administration took it for granted that the Russians , like ourselves , considered it unthinkable that the United States would launch a first strike against them . But the more experience I had with Soviet leaders and other heads of state who knew them , the more I began to realize that many Soviet officials feared us not only as adversaries but as potential aggressors who might hurl nuclear weapons at them in a first strike . . . Well , if that was the case , I was even more anxious to get a top Soviet leader in a room alone and try to convince him we had no designs on the Soviet Union and Russians had nothing to fear from us . " It has been described as the " high point " of the Cold War by Raymond L . Garthoff .