In the fall of 1983, there were a number of incidents that "documentaries" like to say ratcheted up the tension between the Soviets and NATO. But these documentaries often suggest that the Korean Airlines incident, the Grenada invasion, the Able Archer exercise, the Stanislav Petrov incident happened in overlapping timeframes, but in reality none of these events were simultaneous.
How dangerous was the threat?
The Fall of 1983 is often dramatized in popular history and film because it lends itself well for it. The idea is that in a world, very similar to ours in terms of color television and jeans - but where the Soviet Union still exists as a superpower, we are inches away from WWIII or a nuclear winter without most people even realizing it.
This myth drew on various sources and ingredients. At the time, an MI5-MI6 mole inside the Soviet KGB Residency in London, Oleg Gordievsky, warned of the hysterical ''paranoia'' taking over the Kremlin as a result of the confrontational policies of the UK under Thatcher and the US under Reagan, and informed Western intelligence of the existence of a sinister program called VRYaN or alternatively known as RYAN. More about this later.
For the public, the tensions were particularly visible due to the continued breakdown of Detente diplomacy since 1979, with the Soviet invasion of Afghanistan, the subsequent boycott of the Moscow Olympics in 1980, and the implementation of NATO's Dual Track policy, which included the stationing of cruise and Pershing missiles in Western Europe in 1983, leading to the largest demonstrations in the history of many Western countries. This needs to be seen in the context that Detente and nuclear disarmament was very much a European idea, as European leaders (both East and West), increasingly realized since the 1960's that any kind of nuclear strategy involved using Europe as wasteland. The failure of Detente by the late 1970s, and the return of the nuclear arms race by 1983, was seen as a return to 1950's thinking that threatened the very existence of Europe. Hence people in the European capitals staged enormous protests against the return of this kind of diplomacy. The accompanying demagoguery and hostile rhetoric coming from both the White House and the Kremlin in 1983 further cemented this image of extreme tension.
Stories such as the one about Stanislav Petrov, ''the man who saved the world'', further contributed to the myth-making after the Cold War that allegedly, the world was on the brink of war, and one simple man doing his job allegedly saved us all. The real story was a little more complicated than that, but the public very much wants to hear stories about ordinary people who turned out heroes. Especially for documentaries, which are in the first place an entertainment product that need a gripping plot with protagonists and antagonists, 1983 lends itself particularly well for non-fiction Cold War drama.
The reality, as you already suggested in your question, was a lot more sobering. In 1983, no one in the Kremlin, and least of all within the Soviet upper military ranks, ever thought there was going to be a war. In fact, as some Soviet generals have stated, the Soviet military had already by the early 1970's concluded the Cold War would never turn into a direct war. Operation RYAN is sometimes misunderstood and cited as evidence that the Soviets allegedly believed war was imminent. The rather selective Gordievsky revelations of the program have partly caused this, although I must stress that the top-level decision-making process surrounding the program remains a bit foggy.
Sometimes it has been suggested, even by historians, that somewhere in May or April 1981, Soviet leaders grew paranoid - allegedly by Reagan's policies and rhetoric, and called into existence a program to detect a ''Surprise Nuclear Missile Attack'', RYAN. This was a joint program of the KGB and GRU, and all Warsaw Pact allies were also part of it. After the danger of war subsided in 1984, the program was allegedly scaled down too. This is the narrative that emerged in the 1990's based on incomplete information, coming mainly from Gordievsky's instructions he received in London, and the books he published from 1990 onwards. Andropov, the KGB chief, had allegedly held an alarmist speech in 1981 before a KGB Congress in which he warned a Western attack was imminent.
Today we have Andropov's actual speech, and he did not ever say he believed a war was imminent. Moreover, although RYAN was announced as a centralized program in 1981, the Soviet phrase ''Vnezapno Raketnoe Yadernoe Napadenie'' or surprise missile attack, had been frequently used since the early Cold War as a priority for the KGB to detect. In the world of intelligence, this is simply considered ''Early Warning'' or ''Strategic Warning''. The US already centralized its early warning systems in the 1960's. The KGB and GRU, with their typical lack of analytical capacity, did collect intelligence relating to early warning, but lacked a well-developed centralized analytical program to monitor all the signs and information that could reveal a NATO surprise attack. By the late 1970's, the KGB was expanding its use of computer and data analysis (Directorate I within the 1st Chief Department of KGB), largely placed under supervision of Lev Shapkin.
US naval excercises carried out in early 1981 probably alarmed the KGB and GRU to the extent of how unprepared their mechanisms were to detect surprise attacks by NATO, and have probably accellerated the decision to modernize the Soviet strategic warning intelligence in a haphazardly created program with original acronym RYAN. At the conference of the KGB that year, the Soviet leaders probably wanted to stress how important it was to remain vigilant as the US and NATO became increasingly confrontational. Lacking any good human sources close to US and NATO decision-making themselves, the KGB and GRU went on a frantic collection effort of any sign that might announce Western plans for an attack, especially those officers who had been abroad and had no idea what was behind this sudden call to look for signs of danger. By 1984, when some authors claim the program was scaled down, it actually was getting just fully operational, with regular reports (from the entire Warsaw Pact intelligence community) flowing to a central analytical organ within the KGB. For instance, the East German Stasi's RYAN program (KWA), was not active until 1985, while the Stasi was the KGB's main source for intelligence on NATO. The man who coordinated these efforts with the agencies of other Warsaw Pact allies was once again comrade Lev Shapkin. Many of the embryonic analytical sections were suddenly transformed into RYAN sections, and the regular early warning reporting was not ended until 1991, when the Cold War threat had disappeared almost entirely.
In short, RYAN was partly a response to the realization within the Soviet bloc that its early warning mechanisms were badly prepared for a surprise attack, against the backdrop of an intensifying Cold War, and represented a major effort to centralize and expand the analytical capacities of the Warsaw Pact intelligence community. When in 1983 many accidents and crises occurred in a relatively short sequence after eachother, it may be tempting upon reflection to imagine a crisis-like atmosphere in which both the US and USSR had their finger on the red button in a major Great Power staredown. That image is mostly just what it is, an imagination. It did have the polarizing effect of sharpening the division between doves and hawks on both sides of the Iron Curtain. What no one could know back then was that beneath the surface in Moscow, power struggles were being waged over the issue of Detente and the relations with the West, and the tensions of 1983 mainly strengthened the comeback of the hardliners within the Communist Party, who had been suffering some defeats under Andropov as he had been promoting reform-minded youngsters (including Gorbachev). The year 1983 and Andropov's subsequent death in 1984 put the reformers in the antechamber of power while the declining and aging hardliners clung to power, until the path was finally cleared for Gorbachev in 1985 and reforms were underway in 1986. The crises of 1983 were mostly diplomatic in nature, but it would be an exaggeration to speak of an actual threat of war such as during the Cuban Missile Crisis.