American troops in Iraq are reporting a series of incidents in which servicemembers have been blinded or required medical treatment after friendly-fire laser injuries.

According to an Army news release from Balad, Iraq, one unit in Iraq — the 3rd Sustainment Command (Expeditionary) — "has experienced 12 green laser incidents involving 14 soldiers and varying degrees of injury."

The release quotes Capt. Russell Harris, a troop commander with 3rd ESC, as saying that Soldiers have experienced "temporary blindness, headaches and blurred vision."

U.S. troops often use lasers either to target weapons such as rifles, or to "mark" targets that are to be hit by heavier weapons or airstrikes. Lasers have also been used at security checkpoints and in convoys to warn off drivers.

According to Wired Magazine’s Danger Room blog, laser injuries are more common when units first deploy and might be the result of inadequate training.

While various lasers have been used by troops, some are powerful enough that they have "hazard distances" of around 1,500 meters — that is, can cause eye damage from up to 1 mile away.