A nuclear close call is an incident that could lead to at least one unintended nuclear detonation/explosion. These incidents typically involve a perceived imminent threat to a nuclear-armed country which could lead to retaliatory strikes against the perceived aggressor. The damage caused by international nuclear exchange is not necessarily limited to the participating countries, as the hypothesized rapid climate change associated with even small-scale regional nuclear war could threaten food production worldwide—a scenario known as nuclear famine. Despite a reduction in global nuclear tensions after the end of the Cold War, estimated nuclear warhead stockpiles total roughly 15,000 worldwide, with the United States and Russia holding 90% of the total. Although exact details on many of these nuclear close calls are hard to come by, the analysis of particular cases has highlighted the importance of a variety of factors in preventing accidents. At an international level, this includes the importance of context and outside mediation; at the national level, effectiveness in government communications, and involvement of key decision-makers; and, at the individual level, the decisive role of individuals in following intuition and prudent decision-making, often in violation of protocol.
It is critical to note that there have been several instances where nuclear war has been a possibility and we cannot look at these instances as simply being rationally avoided. The role of luck has also been key in cases where ultimately the right decision was made due to wrong information or ignorance. Our knowledge about nuclear weapons safety and command and control are limited and also reflect why the retrospective analysis of nuclear close calls doesn’t depict the whole truth. The vulnerabilities of our knowledge about control and safety of nuclear weapons must be a variable in understanding the occurrence of close calls and how we proceed to analyze them. As Scott Sagan has argued about the Cuban missile crisis, "Many serious safety problems, which could have resulted in an accidental or unauthorized detonation or a serious provocation to the Soviet government, occurred during the crisis. None of these incidents led to inadvertent escalation or an accidental war. All of them, however, had the potential to do so." Therefore, the record of absence of war that has been maintained should not be reduced to simply good management of threats.
Knowledge and learning about close calls
The most common mistakes made about the learning of nuclear close calls are that it's adequate, complete, and unanimous and it’s important to question all three assumptions. Learning about the Cuban missile crisis cannot be regarded as adequate because of the key role played by luck. Luck is too often taken as a confirmation that nuclear deterrence kept the peace but luck should not be misread as successful deterrence. There were instances during the Cuban missile crisis where lack of information, misperception, and ideology could have led to disaster had luck not played the role that it did, including one that former US Secretary of Defense Robert McNamara has been vocal about. Including luck in a successful deterrence strategy, therefore, acts as both a conceptual confusion and a retrospective illusion which has also prevented an adequate learning about the Cuban missile crisis. The learning about the Cuban missile crisis is not complete because the United States is the only country that has been transparent. Efforts to declassify information are not linear and attempts at reclassification sporadic. Additionally, probability is only part of the risk equation. For some, the high consequences of a nuclear detonation will always be too high a risk. How close is “too close for comfort”?' and ‘at what point would the risk be assessed as acceptable or comfortable?’ are two important interconnected questions for two reasons: the abstract nature of the nuclear threat and its devastating consequences are fuelling the temptation to ignore it, and the rhetoric of deterrence is often framed as defensive and seemingly risk-free. The learning about the Cuban missile crisis is not unanimous. Different countries had different experiences of the crisis although it is still considered to be the single most devastating event in nuclear history. The opening of archives worldwide after fifty years suggests that this diversity of interpretations of the crisis is going to remain and possibly increase, without exposing as an illusion the belief that we have already learned what we need to in order to successfully deal with similar events in the future. Documents in those archives suggest that there existed very diverse experiences and interpretations of nuclear vulnerability during the crisis, which are likely to lead to very different conclusions. For example, in the United Kingdom, the elites were well aware of their nuclear vulnerability at the time and saw the possibility of escalation to an all-out nuclear war while the French barely experienced fear of nuclear war.
Close calls and deterrence
An argument in favour of deterrence has been that nuclear weapons have deterred great powers from waging war against each other, so a world without nuclear weapons will lead to, or at least might encourage, great-power war and but this position, and several others in favour of deterrence, have been criticised heavily. Close calls, in particular, should not be simply seen as instruments of deterrence, as deterrence theorists tend to, since reducing their significance to serving deterrence prevents us from taking accidents and unpredictability into account. It’s important to note that there are no reliable records of nuclear weapons accidents or close calls in most nuclear-weapon states. Therefore, interpreting close calls as successful deterrence leads us to make false conclusions. In a number of cases, nuclear weapons have encouraged more risk-prone behaviour. In other words, nuclear deterrence can require leaders to get closer to the brink of disaster to make their deterrent threat more credible. This is a list of known nuclear close calls and other related nuclear incidents in chronological order.
During the Suez Crisis, the North American Aerospace Defense Command (NORAD) received a number of simultaneous reports—including unidentified aircraft over Turkey, Soviet MiG-21s over Syria, a downed British bomber, and unexpected maneuvers by the Soviet Black Sea Fleet through the Dardanelles—that appeared to signal a Soviet offensive. Considering previous Soviet threats to utilize conventional weapons against France and Great Britain, U.S. forces believed these events could trigger a NATO nuclear strike against the Soviet Union. In fact, all reports of Soviet action turned out to be erroneous, misinterpreted, or exaggerated. The perceived threat was due to a coincidental combination of events, including a wedge of swans over Turkey, a fighter escort for the Syrian president, a British bomber brought down by mechanical issues, and scheduled exercises of the Soviet fleet.
5 October 1960
Radar equipment in Thule, Greenland mistakenly interpreted a moonrise over Norway as a large-scale Soviet missile launch. Upon receiving a report of the supposed attack, NORAD went on high alert. However, doubts about the authenticity of the attack arose due to the presence of Soviet leader Nikita Krushchev in New York as head of the USSR's UN delegation.
24 November 1961
Staff at the Strategic Air Command Headquarters (SAC HQ) simultaneously lost contact with NORAD and multiple Ballistic Missile Early Warning System sites. Since these communication lines were designed to be redundant and independent from one another, the communications failure was interpreted as either a very unlikely coincidence or a coordinated attack. SAC HQ prepared the entire ready force for takeoff before already overhead aircraft confirmed that there did not appear to be an attack. It was later found that the failure of a single relay station in Colorado was the sole cause of the communications problem.
27 October 1962
At the height of the Cuban Missile Crisis, Soviet patrol submarine B-59 almost launched a nuclear-tipped torpedo while under harassment by American naval forces. One of several vessels surrounded by American destroyers near Cuba, the B-59 dived to avoid detection and was unable to communicate with Moscow for a number of days. The USS Beale began dropping practice depth charges to signal the B-59 to surface, however the Soviet submarine took these to be real depth charges. With low batteries affecting the submarine's life support systems and without orders from Moscow, the commander of the B-59 believed that war may have already begun and ordered the use of a 10 kiloton nuclear torpedo against the American fleet. The submarine political officer agreed, but commander of the sub-flotilla Vasili Arkhipov persuaded the captain to surface and await orders.
On the same day, an American U-2 spy plane was shot down over Cuba, and another U-2 flown by U.S. Air Force Captain Charles Maultsby strayed 300 miles into Soviet airspace. Despite orders to avoid Soviet airspace by at least 100 miles, a navigational error took the U-2 over the Chukotka Peninsula, causing Soviet MIG interceptors to scramble and pursue the aircraft. American F-102A interceptors armed with GAR-11 Falcon nuclear air-to-air missiles (each with a 0.25 kiloton yield) were then scrambled to escort the U-2 into friendly airspace. Individual pilots were capable of arming and launching their missiles.
9 November 1965
The Command Center of the Office of Emergency Planning went on full alert after a massive power outage in the NE United States. Several nuclear bomb detectors—used to distinguish between regular power outages and power outages caused by a nuclear blast—near major U.S. cities malfunctioned due to circuit errors, creating the illusion of a nuclear attack.
23 May 1967
A powerful solar flare accompanied by a coronal mass ejection interfered with multiple NORAD radars over the Northern Hemisphere. This interference was initially interpreted as intentional jamming of the radars by the Soviets, thus an act of war. A nuclear bomber counter-strike was nearly launched by the U.S.
9 November 1979
A computer error at NORAD headquarters led to alarm and full preparation for a nonexistent large-scale Soviet attack. NORAD notified national security adviser Zbigniew Brzezinski that the Soviet Union had launched 250 ballistic missiles with a trajectory for the United States, stating that a decision to retaliate would need to be made by the president within 3 to 7 minutes. NORAD computers then placed the number of incoming missiles at 2,200. Strategic Air Command was notified, nuclear bombers prepared for takeoff, and intercontinental ballistic missile (ICBM) crews were presumably placed on alert. Within six to seven minutes of the initial response, satellite and radar systems were able to confirm that the attack was a false alarm. It was found that a training scenario was inadvertently loaded into an operational computer. Commenting on the incident, U.S. State Department adviser Marshall Shulman stated that "false alerts of this kind are not a rare occurrence. There is a complacency about handling them that disturbs me." In the months following the incident there were 3 more false alarms at NORAD, 2 of them caused by faulty computer chips.
15 March 1980
One of four Soviet missiles launched from a submarine near the Kuril Islands is detected by an American early warning sensor and determined to be heading towards the United States.
26 September 1983
Several weeks after the downing of Korean Air Lines Flight 007 over Soviet airspace, a satellite early-warning system near Moscow reported the launch of one American Minuteman ICBM. Soon after, it reported that 5 missiles had been launched. Convinced that a real American offensive would involve many more missiles, Lieutenant Colonel Stanislav Petrov of the Air Defense Forces refused to acknowledge the threat as legitimate and continued to convince his superiors that it was a false alarm until this could be confirmed by ground radar.
25 January 1995
Russian President Boris Yeltsin became the first world leader to activate a nuclear briefcase after Russian radar systems detected the launch of a Norwegian Black Brant XII research rocket being used to study the Northern Lights. Russian strategic missile submarines were put on alert in preparation for a possible retaliatory strike. When it became clear the rocket did not pose a threat to Russia and was not part of a larger attack, the alarm was cancelled. Russia was in fact one of a number of countries earlier informed of the launch; however, the information had not reached the Russian radar operators.
23 October 2010
Commanders at a U.S. Air Force base in Wyoming lost most forms of command, control, and security monitoring over 50 nuclear ICBMs for approximately 45 minutes. The missiles were taken offline after a suspected hardware problem caused multiple errors with control computers. Although military officials maintain that the missiles remained under control and were not susceptible to outside attempts to gain control, former Air Force launch officer Bruce G. Blair expressed concerns that missiles in this status could be vulnerable to launch attempts by hackers or compromised missile crews.
