A wearable, non-visible identification device that provides reliable, tamper proof, friendly-force identification and intruder detection. The device is integrated as a part of the wearer's uniform and includes a user input surface for periodic entry of a unit- or user-defined pass code. A timeout capability prevents the device and its identification signal from being used if the pass code is not entered within the specified time period. The preferred embodiment uses non-visible optical identification signals for 1-way identification using standard tactical equipment, making the device useful in the field during operations or at temporary security control points away from established bases. Alternative embodiments use radio-frequency, visible and reflective identification signals. All embodiments use identification signaling methods which are effective at safe stand-off distances to minimize the threat to security personnel. The device also supports identification at tactical distances to support identification in the field. Very low cost and low power embodiments for use by security forces in developing nations are described. This invention provides a novel and improved means for defeat of the threat of adversaries or insurgents exploiting stolen or fake uniforms to attack friendly forces.