The term "Broken Arrow" refers to more than a bad John Travolta movie. In military terminology, a Broken Arrow refers to a significant nuclear event — one that won't trigger a nuclear war — but is a danger to the public through an accidental or unexplained nuclear detonation, a non-nuclear detonation or burning of a nuclear weapon, radioactive contamination from a nuclear weapon, the loss in transit of a nuclear asset (but not from theft), and/or the jettisoning of a nuclear weapon.

The mystery of why these people are smiling also persists.

30. January 21, 1968 - Thule, Greenland

A B-52 from Plattsburgh AFB, New York crashed and burned seven miles southwest of the runway while on approach to Thule AB, Greenland, killing one of its crew members. All four nuclear weapons carried by the bomber were destroyed by fire, contaminating the sea ice. 237,000 cubic feet of contaminated snow, ice, water, and crash debris were moved to the U.S. for storage over a four month cleanup operation as Danish authorities monitored the effort.

31. "Spring, 1968" - "At Sea, Atlantic"

"Details remain classified."

32. September 19, 1980 - Damascus, Arkansas

During routine maintenance of a Titan II missile silo, an Airman dropped a tool, which fell and struck the missile, causing a leak in a pressurized fuel tank. The entire missile complex and surrounding area were evacuated with a team of specialists from Little Rock AFB called in for assessment. 8 1/2 hours after the initial damage, the fuel vapors exploded, killing one member of the team and injuring 21 other Air Force personnel. Somehow, the missile's re-entry vehicle (and the warhead) was found intact, with no contamination.

Stockpiles of nuclear weapons in the global "Nuclear Club" of the U.S., Russia, the UK, France, China, Israel, India, Pakistan and North Korea number 15,600.

Below is a video detailing every nuclear blast ever detonated on Earth:

NOW SEE: The 7 Weirdest Nuclear Weapons Ever Developed

OR:  That One Time the US Detonated a Nuke Right Over a Bunch Of Soldiers