All deaths in war are regrettable, but there's an extra element of sadness when death comes from a mistake, and from an ally. As Chris Michel of Military.com points out on today's show, a large percentage of American troops killed in battle in the 20th century were killed by friendly fire.

Technology has become a double-edged sword with regard to friendly fire. Bombs are now guided by lasers, missiles directed using global positioning. The enemy is not in our sights anymore. The distance from the target might make it inevitable that mistakes occur.

At the same time, IFF (Identification, Friend or Foe) systems provide an encrypted means of discerning where friend and foe can be found. Various other methods (both high and low tech) for combating friendly fire are being developed or used in training to ultimately eliminate friendly-fire casualities.

Military.com has compiled a special webpage that outlines the history of friendly fire along with various detailed technological and training methods to overcome the problem. Editor's note: Free registration is required to access this webpage.