A trio of United States Air Force airmen no longer have their nuclear certifications, and the U.S. military no longer has a functional intercontinental nuclear ballistic missile — valued at $1.8 million — after the service members had a “mishap” with the warhead back in 2014, according to Pentagon officials Friday.

The USAF released a statement detailing the costly mistake, which they say happened when the Minuteman II nuclear missile became nonoperational after a diagnostic test was run on it at the 90th Missile Wing at F.E. Warren Air Force Base in Wyoming.

This from CNN:

While troubleshooting the issue, the maintenance team chief “mistakenly performed an action not directed by the technical guidance,” the statement said.

Air Force officials did not specifically address whether radioactive material was released when the missile was damaged, but said the incident did not result in any injuries or threaten public safety.

Further details about the nature of the “mishap” are murky, as the full report from the military’s Accident Investigation Board remains classified.

The Air Force insists that the maintenance team chief was properly trained for the task he was performing but made a mistake that resulted in damage to the missile. Following the incident, the airmen were retrained and have returned to duty.

The USAF have stressed that they’ve since “tightened” their operation regarding such expensive weaponry by sharing pertinent information and enhancing “technical guidance” as well as their curriculum that educates their personnel.

As you may recall, the particular broken missile in question is one third of America’s nuclear triad — the other two are submarine-launched missiles and ones strapped on aerial bombers.