While treating a casualty under fire, which action can you perform before moving the casualty?

Applying a tourniquet to control severe bleeding is a crucial action that can be performed before moving a casualty under fire. When a casualty is experiencing life-threatening hemorrhaging, the application of a tourniquet mitigates the risk of death due to blood loss. It is important to address severe bleeding as rapidly as possible to stabilize the casualty and can often be done quickly, even in a chaotic environment.

This action prioritizes the casualty's immediate life needs without exposing the rescuer unnecessarily to danger by moving the casualty before managing critical wounds. Once bleeding is controlled with a tourniquet, it may be safer to consider moving the casualty. Other actions, like administering pain relief or beginning CPR, may require more time or could compromise safety if the situation is still dangerous. Additionally, while it's crucial to create a safer environment for the casualty, removing the helmet is not a priority when severe bleeding is present, as it does not address the immediate life threat. Hence, controlling bleeding with a tourniquet is the right choice in this scenario.