Defined by NATO as “the application of fire, coordinated with the maneuver of forces, to destroy, neutralize or suppress the enemy, degrading their performance below the level needed to fulfill its mission,” suppression or covering fire is one of three types of fire support. Only effective for the duration of the fire, suppression fire usually achieves its effect by threatening casualties to individuals who expose themselves to it.
The following video shows a Shia militia fighter of the Iraqi Popular Protection Units (PPU) being accurately engaged by Islamic State fighters in northern Iraq. Several rounds strike the sandbag fortifications near his head. A few rounds even rip through. The militiaman knows that if he exposes his head, it will be removed by hostile fire, so he is only able to ineffectively blind fire back in the general direction of his foe. The incoming suppressive fire doesn’t strike the fighter, yet the man is still rendered useless in the ongoing gun battle. Crazy.