Broken Arrow (military)

Broken Arrow was a call for all available combat aircraft to attack enemy positions, even those close to the position of U.S. troops. The reason for calling in that order, is because a U.S. position is being overrun and can no longer be defended.

Broken Arrow was a code phrase that a military unit on the ground is facing imminent (or very soon) destruction from enemy attack and all available air forces within range are to provide air support immediately. 

Alternatively, Broken Arrow is a code phrase that refers to an accidental event that involves nuclear weapons, warheads or components that does not create a risk of nuclear war. These include:

 Accidental or unexplained nuclear explosion
 Non-nuclear detonation or burning of a nuclear weapon
 Radioactive contamination
 Loss in transit of nuclear asset with or without its carrying vehicle
 Jettisoning of a nuclear weapon or nuclear component
 Public hazard, actual or implied

In modern culture
The phrase has been used in We Were Soldiers (2002) starring Mel Gibson. 

Part of the plot of the movie is that, at the point of being overrun by the enemy, the military officer (played by Mel Gibson), orders his forward air controller, to call in the air strike, by saying "Broken Arrow". 

Other websites
Broken Arrow at Wiktionary.org

Sources

Category:Military terminology