In 1983, the United States and the Soviet Union came dangerously close to nuclear war. That was the conclusion of a highly classified report issued in February 1991 by the President’s Foreign Intelligence Advisory Board, or PFIAB.

The board, which conducts oversight of the U.S. intelligence community for the White House, interviewed over 75 American and British officials and examined scads of intelligence assessments and other official documents from the early 1980s. The report it produced, entitled “The Soviet ‘War Scare,’ ” served as a retrospective assessment of what many believe was the most dangerous period of the Cold War since the Cuban Missile Crisis.

The PFIAB’s analysis of the war scare begins by discussing Soviet strategic vulnerabilities. By the early 1980s, the Soviets had developed new over-the-horizon radars and launch detection satellites that were capable of giving them 15 to 30 minutes warning in the event of a U.S. nuclear attack. However, the impending deployment of U.S. intermediate-range Pershing-2 missiles to Europe created a new vulnerability for the Soviet Union because the Pershing-2s had the ability to strike hardened targets in the western USSR in as little as eight minutes, too little time for the Soviet leadership to react.

There were also concerns among many in Moscow that the nation’s political turmoil left it vulnerable. The death of ailing Soviet leader Leonid Brezhnev in 1982 and the poor health of his successor, Yuri Andropov, who died in early 1984, raised doubts about whether or not the nation’s political leadership would be up to the task of making a timely decision about how to respond if a U.S. nuclear attack were detected. According to the PFIAB report, “Soviet nuclear release authority during the war scare period (1980-1984) was held captive to the tumultuous series of leadership successions at the very top.”

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The board’s assessment also discusses the Soviets’ reliance on VRYAN, a computer program created in 1979 intended to provide an empirical assessment of the risk of a U.S. first strike based on a broad array of military, political, and economic indicators.

The acronym VRYAN stands for Sudden Nuclear Missile Attack in Russian. The underlying belief was that if the United States were ever to achieve “decisive, overall superiority” against the Soviet Union, it could be tempted to launch a first strike against the USSR.

The program’s designers assessed a value of 100 to U.S. economic, military and political power, and they believed that as long as Soviet geopolitical power was 60 or higher, the USSR would be safe from attack. However, VRYAN’s conclusions indicated that Soviet power was declining rapidly relative to that of the United States and was projected to fall to 45 by 1984.

While it remains unclear exactly how much credence the Soviet leadership gave to the computer program’s findings, it was evident by the early 1980s that geopolitical circumstances had taken an unfavorable turn for the Soviet Union. The United States had begun to strengthen its nuclear and conventional forces and reassert itself abroad at a time when the Soviet Union was bogged down in Afghanistan, its economy was faltering, and it was lagging further and further behind the West in the race for advanced technology.

By 1981, high-level Soviet officials had become seriously concerned that the United States might be planning to start a nuclear war. That May, Andropov, at the time the head of the KGB, announced a new joint KGB/GRU initiative – also termed VRYAN – that made the gathering of strategic military intelligence the two agencies’ top priority.

Soviet apprehensions continued throughout 1982 and became especially acute in 1983. According to the PFIAB report, “there apparently was little doubt at the top of the Soviet intelligence services about where U.S. policy was heading.” KGB headquarters sent a new directive to its foreign residencies in February that reemphasized the importance of detecting signs of an impending nuclear attack.

The directive stated that the time between a NATO decision to strike and the actual onset of hostilities would likely be seven to 10 days. The GRU similarly advised its overseas offices that war could break out at any moment. Additional warnings along these lines were issued throughout the year.

Soviet military forces also implemented steps to reduce their vulnerability to attack. At the same time, the rhetoric used by Soviet leaders became increasingly alarmist, with Nikolai Ogarkov, Chief of the General Staff, openly comparing the United States to Nazi Germany. Official Soviet media outlets frequently warned Soviet citizens that war might be imminent, and the general public appears to have believed these pronouncements.

The PFIAB assessment goes on to discuss Able Archer 83, a NATO exercise held from Nov. 7 to 11 simulating the release of nuclear weapons under wartime conditions. This exercise, and the Soviet reaction to it, has been one of the most studied aspects of the war scare. Much of this section of the report is redacted, but the portions that have been declassified indicate that at least some Soviet leaders were concerned that Able Archer 83 was a ruse to conceal preparations for an actual NATO attack.

During the exercise, KGB and GRU residencies abroad were tasked with searching for clues that an attack was imminent, and other Warsaw Pact countries significantly stepped up their intelligence collection as well.

The PFIAB report also notes that Warsaw Pact military activity reached unprecedented levels during Able Archer. “This fact, together with the timing of their response, strongly suggests to us that Soviet military leaders may have been seriously concerned that the U.S. would use Able Archer 83 as a cover for launching a real attack.” Naturally, no such attack took place, or was ever even contemplated, but the war scare persisted well into the next year before finally petering out in the fall of 1984.

The main shortcoming of the PFIAB report is that its discussion of U.S. actions that may have stimulated, or at least reinforced, Soviet fears is limited. Beginning in the early 1980s, U.S. military forces conducted a series of provocative exercises along the Soviet periphery that Moscow surely found alarming.

Often these took the form of sending U.S. bombers over the North Pole – the same route they would take if a war broke out – only to have them turn away just before entering Soviet airspace. The purpose of these exercises, which occurred at irregular intervals, was to keep the Soviets off guard as well as test their reactions. The United States also stepped up its use of aerial reconnaissance flights just outside Soviet airspace, probes that were meant to monitor Soviet military activity.

There was a naval component as well, one whose goal was “keeping the Soviets concerned with threats all around their periphery,” according to Secretary of the Navy John Lehman. In March 1981, Reagan authorized the Navy to conduct operations in waters near the Soviet Union where it had never gone before. That August, a fleet of 83 U.S. and allied ships sailed undetected into the Norwegian Sea, an area heavily patrolled by Soviet forces. Four ships from this task force broke off from the main group and sailed into the Barents Sea near the Kola Peninsula, the site of an extensive complex of Soviet military bases.

Two years later, the U.S. Navy carried out FLEETEX-83, its largest exercise in the Pacific since World War II. Centered around three carrier battle groups, the armada sailed within 450 miles of the Kamchatka Peninsula and Petropavlovsk, the only Soviet naval base with direct access to open seas.

According to Benjamin Fischer, former Chief Historian of the CIA, “U.S. muscle-flexing was almost certainly the cause of Kremlin concern in the first place.” Yet none of these operations are mentioned in the PFIAB report. Its authors note that their investigation “did not specifically match ‘blue force/red force’ activity or probe U.S. strategic deception programs underway at the time. We did, however, learn enough about them to realize such a review would be highly helpful to the study of the Soviet war scare.”

The reasons for this omission are unclear. At the time they were held, information about these exercises was tightly restricted, and in some cases they were authorized orally rather than in writing, leaving little in the way of documentation. As a result, the U.S. intelligence community was largely unaware of them while the war scare was unfolding. Evidently, knowledge of them still remained extremely limited by 1990 when the PFIAB assessment was written.

The report also makes no mention of the potential impact of statements made by U.S. officials that suggested a willingness to fight a nuclear war. During the 1980 presidential campaign, George H.W. Bush, Reagan’s eventual vice president, stated that the United States could prevail in a nuclear conflict as long as it ensured the survival of a portion of its population and industrial capacity. “That’s the way you can have a winner.”