A weapons system is disclosed that provides hot-start navigational information to the Global-Positioning-System receivers on missiles prior to flight. The system comprises a Global-Positioning-System receiver that uses a classified red cryptographic key to decode the P(Y) signal from one or more of the Global-Positioning-System constellation of satellites. Once the P(Y) signal is decoded, one or more characteristics (e.g., the PRN code synchronization, the Doppler shift, the modulation bit sequence, etc.) of the signal is derived. These characteristics of the signal—and some other information including a black cryptographic key that comprises the red cryptographic key—are then provided to the Global-Positioning-System receivers on missiles prior to flight. By giving the missiles this information, the missiles are able to acquire the P(Y) signals themselves more quickly than they otherwise could, which enables them to determine their position more quickly than they otherwise could.