In-Seeker Jamming Device, suitable for an RF missile, utilizes the high-gain antenna and amplifier that are already a part of the missile. During the “blind range” between the termination of the missile's active tracking of the target at a pre-selected distance from the target and its impact on the target, the Jamming Device produces signals that are broadcast via the missile's antenna and are designed to jam and frustrate the active protection system (APS) radars, thereby rendering the APS radars ineffective and the intended targets vulnerable.