The Cold War never became a war. That is the headline fact, and it is easy to mistake it for evidence that the danger was overstated.

It was not. On at least four occasions between 1945 and 1989, the machinery that was supposed to prevent a third world war came close to starting one instead. In three of those cases the decisive factor was not a treaty or a hotline. It was a single person deciding not to do the thing they were entitled to do.

Here are the four moments, and what aviation had to do with each of them.

1. Korea: The General Who Wanted the Bomb

The first crisis arrived barely five years after Nagasaki. When Chinese forces poured across the Yalu in late 1950 and threw United Nations troops back down the peninsula, General Douglas MacArthur asked Washington to consider nuclear weapons and requested discretion to use them.

His target list ran to dozens of aim points, many of them inside China. He floated bombing Beijing. He raised the idea of laying a belt of radioactive material along the Manchurian border as a permanent barrier.

He did not get authorisation. But this was not simply a general talking. In April 1951 Truman released nine Mark 9 warheads to military control, over the objections of the Atomic Energy Commission chairman, Gordon Dean. That October, under Operation Hudson Harbor, B-29s flew practice runs from Okinawa to North Korea with dummy bombs, rehearsing the full sequence of an atomic strike, from weapon assembly through to bomb aiming, to prove the capability worked and to make sure Moscow and Beijing knew it.

Truman fired MacArthur on 11 April 1951. Historians still argue about how much the nuclear question drove that decision, but the effect was to settle a constitutional point that had been dangerously vague: the bomb belongs to the president, not to the theatre commander.

2. Berlin, 1961: Twenty-Four Hours of Loaded Guns

Berlin was the Cold War’s permanent open wound. In 1961 it nearly went septic.

The trigger was almost comically small. On 22 October, the senior American diplomat in West Berlin, E. Allan Lightner Jr., tried to cross into the East at Checkpoint Charlie and was stopped by East German guards demanding to see his papers. Allied policy held that only Soviet officials, not East Germans, had any authority over Allied movement in Berlin. A dispute about a passport became a dispute about who actually governed the city.

On 26 October the US Army moved ten M48 tanks and three M59 armoured personnel carriers up to the checkpoint. The next day Soviet tanks rolled into position opposite them. For more than twenty-four hours the two lines sat roughly a hundred yards apart with their main guns trained on each other, in the middle of a city, in front of a crowd of Berliners who understood exactly what they were looking at.

On the morning of 28 October the Soviet tanks reversed out. The American tanks followed shortly after. Not a shot was fired, no one was hurt, and neither government ever publicly acknowledged the quiet back-channel that arranged the simultaneous withdrawal.

The Wall itself, going up since August, is remembered as the crisis’s brutal resolution. It was an inhuman answer to the refugee problem that had driven Khrushchev’s ultimatums, and it did lower the temperature, because it removed the thing both sides had been escalating over.

How a passport check put American and Soviet tanks muzzle-to-muzzle in a European capital.

3. Cuba, 1962: The Man in the Submarine

The Cuban Missile Crisis is the one everybody knows, and it is usually told as a story about two leaders. The closest call had nothing to do with either of them.

27 October 1962 is remembered as Black Saturday. That was the day Major Rudolf Anderson’s U-2 was shot down over Cuba by a Soviet surface-to-air missile, killing him and removing one of the few remaining excuses not to invade. We have written about Anderson separately, along with the low-level Voodoo reconnaissance runs that kept Washington supplied with imagery.

The same day, far below the surface, the US Navy was dropping practice depth charges on the Soviet submarine B-59 to force it up. The boat had been out of radio contact, its air was foul, the interior temperature was brutal, and the crew had no idea whether the war had already started. B-59 carried a nuclear-tipped torpedo.

Captain Valentin Savitsky ordered it armed. Firing required the agreement of three men, and one of them was Vasili Arkhipov, chief of staff of the submarine flotilla, who happened to be aboard and who outranked Savitsky. Arkhipov argued that the Americans were signalling rather than attacking, on the logic that nobody wastes practice charges on a submarine if a general war is already under way. He refused. The boat surfaced.

The compromise between Kennedy and Khrushchev came together within hours of a decision to strike. It is worth sitting with the fact that the thinnest margin of the entire Cold War came down to one officer in a hot, stale compartment declining to give his consent.

The thirteen days, and how narrowly they resolved.

4. Able Archer 83: The Exercise That Looked Real

The last one is the one almost nobody knew about until the files came out, and it is arguably the most frightening, because nobody involved on the Western side thought anything unusual was happening at all.

Able Archer was NATO’s annual command-post exercise rehearsing the procedures for escalating to nuclear release. The 1983 edition, run in early November and ending on the 11th, was different. It used a new coded communications format, periods of radio silence, and the notional participation of heads of government. It was, in short, extremely realistic.

It landed in the worst possible year. The Soviet leadership was already convinced that Washington might be planning a first strike. Pershing II missiles were arriving in Europe with flight times to Moscow measured in minutes. Soviet intelligence residencies in Western Europe had been ordered to watch for the indicators of an imminent attack, and an exercise designed to look exactly like preparation for a nuclear release generated precisely those indicators.

Moscow acted on what it saw. Aircraft in Poland and East Germany were loaded with nuclear weapons. SS-20 intermediate-range missiles went to high alert. Ballistic missile submarines were moved under the Arctic ice, where they would be hard to find and hard to stop.

NATO finished the exercise on schedule and went home. Only afterwards did Western intelligence work out what the other side had been doing. A subsequent report by the President’s Foreign Intelligence Advisory Board, declassified decades later, did not mince words.

The same review found the Soviet and Warsaw Pact reaction to be “unprecedented”, and described it as activity of a kind seen only during genuine crisis periods. Able Archer had come close to producing a war that neither side wanted, intended, or would have understood until it was under way.

The war game that Moscow read as the real thing.

The Pattern

Look at the four together and something uncomfortable emerges. Only one of them, Cuba, was a deliberate confrontation between leaders who knew they were in a crisis. Korea was a commander pushing beyond his authority. Berlin was a passport check that escalated. Able Archer was a scheduled training exercise that one side could not tell apart from the real thing.

The systems built to prevent nuclear war — alert states, exercises, reconnaissance, early warning — are the same systems that generate the signals the other side reads as aggression. That is not a flaw anyone has solved. It is the structure of deterrence.

And in the moments that mattered, what stopped it was not the system. It was Arkhipov in a submarine, and Stanislav Petrov at a console in Serpukhov-15 a few weeks before Able Archer, deciding that his screens were wrong. Both men were doing the opposite of what their training told them to do, and both were right.

Sources: Wikipedia, National Security Archive, Atomic Heritage Foundation, US Army, Carnegie Endowment for International Peace, Smithsonian Magazine, Imperial War Museums, Bulletin of the Atomic Scientists.