Security tags for shipping containers

A security device for a shipping container including a plurality of walls defining a cargo storing area, one or more doors coupled to at least one of the plurality of walls, at least one door of the one or more doors movable between an open position exposing the cargo storing area and a closed position, and a locking device configured to secure said at least one door in its closed positioned, the locking device defining an opening and including a first fastener and a second fastener, at least one of the first fastener and the second fastener attached to said at least one door, the security device adapted for placement in the opening of the locking device, the security device comprising a neck including a top side, a bottom side and opposing sides defining a width of the neck, the neck insertable through the opening of the locking device, a first wing extending from the top side of the neck, and a second wing extending from the bottom side of the neck, the first wing including opposing sides defining a width, the second wing including opposing sides defining a width, wherein the width of the neck insertable through the opening of the locking device is smaller than the width of the first wing and the width of the second wing, and wherein the first wing and the second wing are adapted to substantially cover the first fastener and the second fastener, respectively, to prevent access to the first fastener and the second fastener when the security device is placed in the opening of the locking device.