The present invention is directed to a system and a method for accurately locating a penetrating-type weapon within a shelter for detonation at a desired target site. The method includes detecting a deceleration threshold event indicative of the penetrating weapon impacting and traversing a layer of shelter having certain material or structural characteristics (e.g., a "hard" or a "thick" layer). A delayed detonation program or process is enabled upon detection of the threshold event. For example, a delayed detonation program or process may include layer counting, void counting, or a combination of layer and void counting until the desired number of layers (and/or voids) of a shelter has been detected, at which time the weapon may be detonated. Any deceleration events that occur prior to the deceleration threshold event are ignored to minimize the potential failure of detecting specific types of layers including certain types of "soft" or "thin" layers.