The M84 stun grenade is a non-lethal weapon used to disorient and subdue enemy combatants.
The M84 stun grenade has been in active service with the U.S. military since 1995. When detonated, it emits a loud "bang" sound and a blinding flash of light. While not lethal, this "flash bang" effect can disorient people and cause temporary blindness, deafness, and inner ear disturbance. These effects can lead to people becoming confused and result in a loss of coordination and balance. This makes it easy for U.S. soldiers to then subdue and restrain enemy combatants in places such as Iraq and Afghanistan.
The M84 stun grenade has a magnesium-based pyrotechnic charge that is fitted inside a thin aluminum case. When detonated the inner-aluminum case is consumed by the pyrotechnic charge and produces a loud bang and bright flash. The grenades are typically used in confined spaces such as buildings and bunkers. The M84 is frequently used in urban warfare and to help resolve hostage situations.
The U.S. Army outlines that the M84 stun grenade should be used "during building and room clearing operations" and when American soldiers are trying to "achieve surprise." Stun grenades are also deployed when civilians are involved to minimize collateral damage and death.
The M84 is incapable of igniting paper or cloth and does not get very hot when ignited. However, the stun grenades can ignite flammable liquids and vapours such as gasoline. Each grenade weighs about eight ounces and is about five inches long and two inches in diameter. The grenades are used across all branches of the U.S. military.