For almost half a century, the world lived under the shadow of nuclear war.
The Cold War was not a conventional war between the United States and Soviet Union. Instead, it was a prolonged geopolitical, ideological, economic, and military struggle between two competing superpowers. The United States and its allies represented a broadly capitalist and liberal-democratic order, while the Soviet Union and its allies represented communist governments organized around Soviet leadership.
Yet the Cold War was never simply "cold." There were wars in Korea, Vietnam, Afghanistan, Africa, and elsewhere. There were confrontations over Berlin and the Middle East. American and Soviet forces frequently operated in close proximity, and both sides supported opposing governments and revolutionary movements around the world.
The greatest danger, however, was the possibility that one of these confrontations could escalate into a nuclear war.
For more on the Cold War, see The Cold War: A Very Short Introduction (Amazon affiliate link)
The Cold War Begins in the Nuclear Age
The Cold War emerged almost immediately after the Second World War.
The United States entered the postwar period as the world's only nuclear power. That monopoly ended when the Soviet Union successfully tested its first atomic bomb on August 29, 1949.
The Soviet test transformed the strategic situation. The United States could no longer assume that the Soviet Union could be deterred simply because America possessed nuclear weapons.
The arms race accelerated.
The United States developed the hydrogen bomb, followed by the Soviet Union. Both sides developed long-range bombers, intercontinental ballistic missiles (ICBMs), submarine-launched ballistic missiles (SLBMs), and increasingly sophisticated nuclear warheads.
The result was eventually a system known as mutually assured destruction, or MAD.
The basic logic was grim but relatively simple: if either side launched a large-scale nuclear attack, the other side would retain enough nuclear forces to destroy the attacker in retaliation.
The goal was therefore not to make nuclear war winnable. It was to make nuclear war irrational.
By the 1980s, the Soviet nuclear stockpile had reached roughly 40,000 warheads. The United States possessed a comparably enormous arsenal.
The paradox was that nuclear weapons were intended to prevent war while simultaneously making any major war between the superpowers potentially catastrophic.
The Nuclear Arms Race
The arms race went through several stages.
During the 1950s, both countries concentrated on developing increasingly powerful bombs and finding ways to deliver them.
The bomber was initially the principal means of delivering nuclear weapons. The development of ICBMs changed this dramatically. A missile could potentially travel from one continent to another in roughly half an hour.
Submarines made the situation even more complicated.
A nuclear-armed submarine could hide beneath the ocean and launch missiles without being easily detected. This created a particularly powerful form of deterrence because destroying an opponent's land-based missiles would not necessarily prevent retaliation from submarines.
By the 1960s, both superpowers were therefore building a nuclear triad:
- Land-based ICBMs
- Submarine-launched ballistic missiles
- Strategic bombers
The system was designed to guarantee a retaliatory capability.
But it also created a frightening problem: nuclear forces were maintained at high levels of readiness because each side feared that waiting too long in a crisis might allow the opponent to destroy its weapons.
This produced a dangerous "use them or lose them" mentality.
Why Didn't Someone Accidentally Launch?
Given the enormous number of nuclear weapons and the tension between the superpowers, an obvious question arises:
Why didn't an accident start World War III?
The answer is that elaborate systems were developed to prevent unauthorized or accidental nuclear use.
One important principle was positive control. Nuclear weapons were not supposed to be usable simply because someone happened to have physical access to them.
The United States developed technical safeguards, including Permissive Action Links (PALs). These devices prevented a weapon from being armed without the correct authorization codes.
There was also the two-person rule. Personnel working with nuclear weapons were generally required to operate in pairs so that one individual could not independently perform critical actions. U.S. archival material documents the use of two-person control and coded devices for American nuclear weapons deployed in Europe.
Command-and-control systems were also designed so that nuclear weapons could not simply be launched because of a local decision.
These safeguards were supplemented by increasingly sophisticated communication and early-warning systems.
But there was a fundamental weakness:
Technology could prevent some accidents, but it could not eliminate human judgment.
A computer could mistakenly report an attack. A radar system could misinterpret an object. A military exercise could be mistaken for a real attack. A commander could misinterpret an order.
And a political leader could make a catastrophic decision.
Early Warning Systems
Both sides constructed enormous early-warning networks.
The United States and Soviet Union used radar, satellites, intelligence networks, and other systems to detect possible enemy missile launches.
The logic was straightforward.
If an enemy launched hundreds of missiles, there would be only minutes to determine what was happening and decide how to respond.
But this created another danger.
The shorter the warning time became, the greater the possibility that a false alarm could trigger a real response.
The Cold War therefore created a peculiar situation in which computers and warning systems were designed to prevent surprise attacks while simultaneously creating new opportunities for catastrophic mistakes.
And there were mistakes.
False Alarms in the United States
The United States experienced several false warnings of Soviet missile attacks.
In 1979, a training scenario was inadvertently introduced into the American warning system, creating indications of a large-scale Soviet attack.
In 1980, a faulty computer chip contributed to false indications of a massive Soviet missile launch.
These incidents did not result in nuclear war because additional systems and human operators determined that the warnings were false.
But they demonstrated an important reality:
The danger did not necessarily require an enemy to attack.
A computer error could potentially start the process.
The Cuban Missile Crisis
The closest the Cold War came to nuclear war was the Cuban Missile Crisis of October 1962.
The Soviet Union secretly began placing nuclear missiles in Cuba, approximately 90 miles from the American coast.
The strategic situation was complicated.
The United States already possessed nuclear weapons capable of striking the Soviet Union. American nuclear missiles were also deployed in countries near the Soviet Union, including Turkey.
For Soviet leader Nikita Khrushchev, placing missiles in Cuba could help protect Fidel Castro's revolutionary government while also altering the strategic balance.
For President John F. Kennedy, Soviet nuclear missiles in Cuba were unacceptable.
When American reconnaissance aircraft discovered the missile installations, Kennedy faced an extraordinarily difficult decision.
He could:
- Do nothing
- Negotiate
- Attack the missile sites
- Invade Cuba
- Establish a naval blockade or "quarantine"
Kennedy chose the quarantine option.
But this was extraordinarily dangerous.
A direct American attack could kill Soviet personnel in Cuba. The Soviet Union might retaliate against American forces or interests elsewhere. The conflict could then escalate rapidly.
American forces were placed at DEFCON 2, one step below the highest level of military readiness. The United States had never gone to DEFCON 1 during the Cold War.
For thirteen days, the world waited.
Black Saturday
The most dangerous day of the crisis was probably October 27, 1962—often called Black Saturday.
Multiple dangerous events occurred almost simultaneously.
An American U-2 reconnaissance aircraft was shot down over Cuba, killing pilot Major Rudolf Anderson.
American military leaders were pressing Kennedy toward stronger military action.
Meanwhile, Soviet and American ships were confronting one another around Cuba.
But one of the most frightening incidents occurred beneath the Atlantic Ocean.
A Soviet submarine, B-59, was operating near the American naval quarantine line. The submarine was being subjected to depth charges intended to force it to surface.
The submarine's crew had lost contact with Moscow and did not know whether war had begun.
The submarine was also carrying a nuclear torpedo.
The situation was extraordinarily dangerous because the crew could have concluded that war had already begun.
According to the historical account, the decision to use the nuclear weapon required agreement among the senior officers aboard the submarine. Vasili Arkhipov opposed launching the weapon and helped prevent the situation from escalating.
The incident illustrates one of the most disturbing realities of the Cuban Missile Crisis:
At certain points, events were no longer completely under the control of Kennedy or Khrushchev.
Military personnel, submarines, aircraft, ships, and local commanders were all operating within an extraordinarily tense environment.
A single miscalculation could have changed history.
How the Crisis Ended
Kennedy and Khrushchev ultimately found a way out.
The Soviet Union agreed to remove its missiles from Cuba.
The United States publicly promised not to invade Cuba.
Privately, the United States also agreed to remove its Jupiter missiles from Turkey.
The crisis ended without nuclear war.
But both Kennedy and Khrushchev had learned a terrifying lesson.
The world had come far too close to destruction.
The crisis also demonstrated that communication was essential.
The two governments subsequently established a direct communication link between Washington and Moscow, popularly known as the Hotline. The experience also encouraged the two superpowers to pursue arms-control agreements.
The Limited Test Ban Treaty
One of the first results was the Limited Test Ban Treaty of 1963.
The treaty banned nuclear tests in the atmosphere, outer space, and underwater.
It did not end the arms race. Both countries continued developing nuclear weapons and conducting underground tests.
Nevertheless, it was an important change.
The United States and Soviet Union had demonstrated that cooperation was possible even while they remained ideological enemies. The treaty became the first in a series of Cold War arms-control agreements.
Later agreements included the Nuclear Non-Proliferation Treaty, SALT I, the Anti-Ballistic Missile Treaty, SALT II, the Intermediate-Range Nuclear Forces Treaty, and the Strategic Arms Reduction Treaty.
The arms race continued, but it was increasingly accompanied by attempts to manage it.
The 1983 Nuclear Scare
The Cuban Missile Crisis was the closest the superpowers came to nuclear war, but the 1980s produced several frightening incidents.
The early 1980s were particularly tense.
Ronald Reagan adopted a confrontational policy toward the Soviet Union. The United States expanded military spending and deployed new weapons systems, while NATO deployed Pershing II and cruise missiles in Europe.
The Soviet leadership was deeply suspicious of American intentions.
Then came Able Archer 83.
Able Archer was a NATO exercise designed to practice procedures associated with a nuclear conflict.
From the Western perspective, it was a military exercise.
But Soviet leaders and intelligence officials were sufficiently concerned about the possibility of a surprise Western attack that the exercise generated a serious war scare.
Declassified material has demonstrated that Soviet forces took unusual measures during the exercise, including heightened readiness among some units. An American intelligence officer, Lieutenant General Leonard Perroots, later recalled Soviet military preparations that were sufficiently unusual that he considered whether the United States should increase its own readiness. He ultimately recommended against doing so.
This may have been extremely important.
Had the United States responded to Soviet preparations by increasing its own military readiness, the Soviets might have interpreted that as evidence that their fears were justified.
The result could have been a dangerous cycle:
Soviet alert → American alert → Soviet response → American response.
That is precisely how an accidental war could begin.
Historians continue to debate exactly how close Able Archer came to producing nuclear war. It should not simply be portrayed as an inevitable moment when the Soviet Union was about to launch its missiles. The historical evidence is more complicated.
Nevertheless, it demonstrated how easily military exercises, intelligence assessments, and political tensions could interact in dangerous ways.
Stanislav Petrov and the False Missile Attack
Only weeks before Able Archer, another potentially catastrophic incident occurred.
On September 26, 1983, Soviet early-warning systems reported that the United States had launched nuclear missiles against the Soviet Union.
The officer on duty was Lieutenant Colonel Stanislav Petrov.
The system initially indicated that five American missiles had been launched.
Petrov had to decide whether the warning represented a genuine attack.
He chose not to treat the computer warning as a confirmed American nuclear strike.
He was right.
The system had produced a false alarm caused by the way Soviet satellites interpreted sunlight reflecting from high-altitude clouds.
Petrov's decision became famous because a different decision could theoretically have sent a warning up the Soviet chain of command during an extremely tense period.
The episode illustrates the importance—and danger—of human beings remaining in the nuclear command chain.
A computer can process information extremely quickly.
But it cannot necessarily determine whether the information makes sense.
Other Dangerous Incidents
The Cold War contained numerous other close calls.
Some involved accidents involving nuclear weapons. Others involved technical failures.
There were aircraft accidents involving nuclear weapons, lost nuclear weapons, submarine accidents, and radar or computer malfunctions.
There were also incidents in which military aircraft or ships came dangerously close to one another.
The danger was therefore not simply:
"What if Kennedy or Khrushchev deliberately decided to start nuclear war?"
It was also:
"What if something goes wrong?"
That distinction is crucial.
Nuclear deterrence depends upon rational decision-making. But the Cold War was populated by thousands of people, machines, organizations, communications systems, intelligence agencies, and military units.
Any one of them could make a mistake.
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Why Didn't Nuclear War Happen?
The simplest answer is that deterrence worked.
Both sides understood that a nuclear war would be catastrophic.
The doctrine of mutually assured destruction created powerful incentives for restraint.
But that is not the entire explanation.
Several additional factors helped prevent nuclear war.
1. Communication
The United States and Soviet Union increasingly developed direct communication channels.
The Hotline was one result of the Cuban Missile Crisis.
2. Arms Control
Treaties did not eliminate nuclear weapons, but they established limits and mechanisms for communication and verification.
The Limited Test Ban Treaty was an early example. Later treaties dealt with strategic weapons, missile defenses, intermediate-range missiles, and nuclear proliferation.
3. Nuclear Command and Control
Both countries developed elaborate procedures intended to prevent unauthorized use.
The American system, for example, included two-person control and technical safeguards such as Permissive Action Links.
4. Redundancy
Nuclear warning systems did not rely upon a single sensor.
Radar, satellites, intelligence reports, and human analysis were supposed to confirm warnings.
This redundancy was essential because no individual system was completely reliable.
5. Human Judgment
Perhaps most importantly, individuals repeatedly questioned information that could have been accepted as genuine.
Stanislav Petrov did so in 1983.
American officers did so during false alarms.
During the Cuban Missile Crisis, Kennedy and Khrushchev repeatedly resisted advisers who wanted more aggressive action.
In several cases, individuals chose caution when the circumstances encouraged escalation.
So, How Close Did We Come?
The answer depends upon what we mean by "close."
If we mean the point when the political leaders of the United States and Soviet Union were most directly confronting one another and actively considering military action, the answer is clearly:
The Cuban Missile Crisis in October 1962.
The U.S. government placed its forces at DEFCON 2. Soviet nuclear weapons were in Cuba. American and Soviet forces were confronting one another. A U.S. aircraft had been shot down. Soviet submarines were operating in the quarantine zone. And both governments were struggling to understand what the other side intended.
The U.S. State Department itself describes the Cuban Missile Crisis as the moment when the superpowers came closest to nuclear conflict.
If, however, we ask when a nuclear war might have been triggered by accident or miscalculation, the answer becomes less straightforward.
The 1983 Petrov incident is an important example.
Able Archer 83 is another.
The numerous false alarms throughout the Cold War demonstrate that the danger was not confined to a single thirteen-day crisis.
The Strange Success of the Cold War
The Cold War is therefore one of history's great paradoxes.
The United States and Soviet Union built weapons capable of destroying civilization.
They repeatedly threatened one another.
They placed nuclear weapons on alert.
They developed plans for nuclear war.
They constructed increasingly sophisticated weapons systems.
And yet they never directly fought each other.
That does not mean nuclear war was inevitable. Nor does it mean that the world survived solely because of luck.
Diplomacy, deterrence, arms control, communication, military procedures, technological safeguards, and—perhaps most importantly—individual decisions all played important roles.
But luck mattered too.
The Cuban Missile Crisis demonstrated how quickly a political confrontation could escape the control of national leaders. The false alarms of the 1970s and 1980s demonstrated that sophisticated technology could itself become a source of danger. Able Archer showed that even a military exercise could potentially be misunderstood.
The most important lesson of the Cold War may therefore be that nuclear deterrence was never simply a mathematical equation.
It depended upon people.
People had to interpret information correctly. They had to question faulty intelligence. They had to resist pressure to escalate. They had to communicate with their adversaries. And, ultimately, they had to decide not to use the weapons they possessed.
The world came closest to nuclear war during the Cuban Missile Crisis, particularly during the terrifying events of October 27, 1962.
But the broader history of the Cold War shows something even more sobering:
There was no single moment when humanity was in danger. For four decades, the nuclear system itself created a continuing possibility that an accident, misunderstanding, or miscalculation could turn the Cold War into a nuclear catastrophe.
That may be the most important thing to remember about the Cold War. The remarkable achievement was not simply that the United States and Soviet Union possessed enough weapons to destroy each other.
It was that, despite repeatedly coming close, they never used them against each other.
