A report recounting a litany of near-misses in which nuclear weapons came close to being launched by mistake concludes that the risk of potentially catastrophic accidents is higher than previously thought and appears to be rising.
"Too close for comfort: Cases of near nuclear use and options for policy", published on Tuesday by London think tank Chatham House, says that "individual decision-making, often in disobedience of protocol and political guidance, has on several occasions saved the day", preventing the launch of nuclear warheads.
The report lists 13 instances since 1962 when nuclear weapons were nearly used. In several cases the large-scale launch of nuclear weapons was nearly triggered by technical malfunctions or breakdowns in communications causing false alarms, in both the US and Russia. Disaster was averted only by cool-headed individuals gambling that the alert was caused by a glitch.
The Chatham House authors say the risks appear to be rising. Nuclear weapons are spreading - most recently to North Korea - and disarmament is stalling. Russia and the US still have an estimated 1,800 warheads on high alert, ready to launch between five and 15 minutes after receiving the launch order - a fact that becomes all the more significant with rising tensions over Ukraine.
"The question today is: are these risks worth it?" asked Patricia Lewis, a Chatham House research director and one of the report's authors.
The mental state of leaders who had their fingers on the nuclear button has sometimes been a concern. Richard Nixon and Boris Yeltsin both worried their top advisers with their heavy drinking.
In May 1981, the newly elected French president, Francois Mitterrand, left the French nuclear-launch codes at home in the pocket of his suit. President Jimmy Carter did the same in the 1970s, and the suit as well as the codes were taken to the dry cleaners. The US launch codes went missing again when Ronald Reagan was shot on March 30, 1981. FBI agents had them, along with the injured president's bloodied trousers.
Tuesday's report focuses on cases in which nuclear weapons came close to being launched deliberately on the basis of bad or incomplete information. However, there is an additional risk of accidents inherent in the maintenance of stockpiles of more than 17,000 warheads held by Russia, the US and the other seven nuclear-armed states.
Some of those accidents were described in a book published last year, entitled Command and Control.
Author Eric Schlosser gives an account of an incident in September 1980 in Arkansas, in which a maintenance engineer dropped a socket wrench into a silo holding a Titan II nuclear missile, igniting its fuel and triggering an explosion that sent the warhead flying. It landed near a road but did not detonate.