Abstract: A blanking-off element, intended to be mounted on one end of a tube for storing and launching a munition to protect its interior from external attacks, embodies a cap intended to extend over the entire section of the tube end and to be fixed in a tight manner right along the edge of the tube end and to become detached at least partially with respect to the end at the moment of launching, characterized in that the cap is fixed to the interior of a protective cover made from pliable material which has a retaining lug fixed to the outside of the tube close to the end, whereby the cap is recovered by the protective cover at the moment of launching.