It is a delivery system that uses a low Earth orbit to bypass early warning systems and deliver warheads on targets very quickly. FOBS launches a warhead into a low Earth orbit trajectory instead of a full ballistic missile arc. These systems are typically designed to detect missiles launched on high ballistic trajectories. A FOBS warhead in a low orbit might be harder to detect until it re-enters the atmosphere for its final approach to the target. Due to the orbital path, the time between re-entry and target impact can be shorter compared to a traditional ballistic missile attack.