Thermal imager aims to help soldiers on the battlefield avoid shooting one of their own.

In every war, soldiers run the risk of being mistaken for the enemy and shot by their own side. A Pentagon contractor is trying to do something about that by selling devices that can help soldiers in the field tell friend from foe.

The problem is widespread. The confusion of war caused five Americans to be injured in northern Afghanistan in late November when a JDAM bomb fell too close to their position outside a prison.

In the Gulf War, 165 soldiers -- 45 percent of American fatalities -- were killed by friendly fire. Of the eight Bradley tanks and tank crews that were lost, friendly fire destroyed seven.

"Fifteen to 25 percent of all fatalities in any conflict are the result of fratricide or friendly fire," said Harvey Novak of Falcon Systems Engineering.

Novak's scientists are trying to reduce the number of friendly-fire fatalities by manufacturing infrared markers that can be seen as thermal images from miles away. They can be worn as armbands or manufactured as beacons that mount on vehicles. Scientists say they hope the markers will result in easier and more accurate life-and-death decisions on a battlefield.

Novak offers the example of a tank on a battlefield. With friendly forces wearing the markers, a gunnery officer can see that someone is lit up and knows not to shoot. Fighters without identifiers become targets.

The markers would be of particular value to the increasing number of units using thermal imaging to detect the presence of human beings. All new Bradley tanks and all Apache helicopters now have thermal-imaging cameras. However, the thermal images are indistinct, with individual characteristics difficult to see.

"You can't see color, you can only see gradations or differences in the amount of infrared light being emitted by the object. A person will look kind of like a ghost," Novak said.

Because thermal images are based on heat, a big challenge was to keep the markers cool enough for soldiers to wear. The Falcon spokesman will not say how, but the company engineered the markers so the back is cooler than the front, making it more wearer-friendly.

Soldiers have given Novak positive feedback about the technology.

"It's really chilling when somebody looks at you and says, 'You know, if we'd have had the use of these in some of the conflicts we've been in, some of my buddies would still be alive,'" he said.

The military seems convinced. It has ordered hundreds of markers for testing, hoping the technology will help US soldiers avoid shooting their friends in the desperate confusion of war.