A safe and arm (S&A) device is disclosed. The device utilizes a no-fire separation distance and a mechanical configuration of primary explosive/booster explosive and secondary explosive to establish a safe mode. While in safe mode, the device would allow no more than 1 in 1 million detonation transfers to occur from primary to secondary. In armed mode, the no-fire separation distance is taken away, allowing reliable detonation transfer. Two arming environments, which occur after launch and safe separation, are used to move the S&A device to armed mode. The first environment is the release event of the projectiles from their packed state in a dispenser. The second environment is a target sense mechanism. If either arming environment returns to its original state, the mechanism returns to safe mode. The S&A device will not allow inadvertent packing into the dispenser of explosive devices in the armed state.