Fratricide — where one side kills its own in combat — is a curse of the technologically advanced. They are most likely to have the beyond-visual-range, fast weapons — and the need for batteries to summon a bomb from the heavens — that make it more likely…

“The fact that the percentage of casualties resulting from friendly fire from World War I through Vietnam has been extremely low does not make the accidental killing or wounding of one’s own troops any less tragic or unpalatable,” a 1982 Army report said. “There is reason to believe that the casualties attributable to friendly fire in modern war constitute a statistically insignificant portion of total casualties (perhaps less than 2%).”

Weapons got better faster than the trigger fingers firing them. “While modern weapons have furthered the military’s combat firepower, technology that can help U.S. fighting personnel maintain situational awareness and differentiate between friends and foes in difficult combat conditions has lagged,” a 1992 Army paper noted. But doctrine — how and when to use force — and training — how to use it properly — are just as critical in reducing friendly fire as technology, military officers say.