For example France doesn't rely on GPS for military purpose, mostly using inertial positioning systems that drift and require re-calibration. (sometimes with dr

For example France doesn't rely on GPS for military purpose, mostly using inertial positioning systems that drift and require re-calibration. (sometimes with dramatic effects like when 2 soldiers got killed in the wrong country in Africa because they had drifted) There is a giant network of ground stations around the world so that french submarine can re-calibrate their positioning system periodically. It's a unique solution that only works when you have territories all over the world, since you don't want to position your nuclear power with a foreign system.