You'll be relieved to know that the public was never put in danger by a nuclear weapons incident that caused $1.8 million (£1.3 million) in damages to a Minuteman III missile in Colorado. But the accident, which happened in May of 2014, initially went unreported by the US Air Force even as a team of experts reviewed the service's nuclear forces in the wake of a testing scandal and security failures.

The Associated Press received what it called "the first substantive description of the accident" last Friday following more than a year of requests to the Air Force.

Details of the incident have been kept secret by the Air Force because of their sensitive nature, but we now know the situation rendered an intercontinental ballistic missile inoperable. Three airmen were trying to troubleshoot the missile after it failed a diagnostic test and had become "non-operational." Ultimately, the accident would likely have been categorized as a "Bent Spear" event, the code used by the military for damaged weapons (as opposed to "Broken Arrow," the code for an accidental nuclear detonation or other weapons incident in peacetime).

According to the Air Force, the missile was partially damaged in this troubleshooting process because the maintenance chief "did not correctly adhere to technical guidance" and "lacked the necessary proficiency level" to understand that what was being done to find the problem could cause greater damage to the missile.

The 2014 independent review of the Air Force's "nuclear enterprise" found widespread morale problems and deteriorating hardware. At the time, then-Secretary of Defense Chuck Hagel said the report found that "a consistent lack of investment and support for our nuclear forces over far too many years has left us with too little margin to cope with mounting stresses. The reviews found evidence of systematic problems that if not addressed could undermine the safety, security, and effectiveness of the elements of the force in the future."

While expensive, the May 2014 incident at the "Juliet-07" silo—nine miles outside Peetz, Colorado—is hardly the most serious incident to have occurred within the Air Force's nuclear forces. The service went through a wave of missile safety improvements in the 1980s after the "Damascus Incident," when a technician dropped a socket wrench and triggered the explosion of a Titan II ICBM in Damascus, Arkansas. The wrench struck the missile as it fell and pierced the skin of its booster, causing fuel and oxidizer leaks. The resulting explosion killed one airman, injured 21 others, and ejected the W-53 nuclear warhead from the silo. The warhead landed next to a nearby road. The Titan II missiles were phased out in the 1980s as the LGM-118 "Peacekeeper" missile was being introduced.

But since the 1980s, there's been little in the way of technology updates for the US ballistic missile force. The Minuteman III missile damaged in the newly uncovered incident entered service in the 1970s. While the 450 Minuteman III missiles have had significant upgrades over the past three decades (including a new guidance system in 1993), most of the billions spent on them has been to refurbish their existing technology. The network linking together the command bunkers for the Minuteman III fleet uses software that is stored on 8-inch floppy disks.

Fortunately, there have been no explosive accidents with nuclear weapons since 1958, when a B-52 accidentally released an unarmed nuclear bomb over South Carolina. Luckily, in that event, the fissile core of the bomb was not installed. However, the bomb's conventional explosive trigger did go off, causing an explosion that damaged a nearby house when it struck the ground and created a crater 70 feet wide and 35 feet deep. Given the number of other accidentally dropped or explosively launched nuclear warheads over the past 60 years, it's a testament to the engineering behind US nuclear warhead design that there hasn't been an accidental atomic explosion. You have to look on the bright side of these things.