A couple of points: What has RF jamming of GPS signals got to do with "Cyber"? If someone were to hack the GPS control system, that would be "Cyber", but that's not what this article is about. Clearly some folks haven't read the linked article. GPS signals are very weak, so relatively easy to jam. (e)LORAN uses much high power signals than GPS, therefore is less susceptible to jamming. In the event of a war, if the adversary has the capability to destroy GPS satellites in space, it's unlikely eLORAN beacons on the ground will survive very long. Not sure why the continental US would consider they need eLORAN coverage as any localized GNSS jamming could be dealt with. (RDF to jamming sources) I can appreciate why such a backup system seems a prudent idea around the Korean Peninsula at the moment. It seems conceivable that carrier signals from non-GNSS satellites in geosynchronous orbit (not in Low/Medium Earth Orbit) could be used non-high precision navigation. Not sure what the positional accuracy would be, but eLORAN isn't high precision. It would be very difficult to render all satellites usable for navigation inoperative. Given the existing and proposed constellations for GPS (32), GLONASS (24), BeiDou-2 (30) and Galileo (30), while it may be possible to create a temporary hole in system coverage, eliminating enough satellites to shutdown GNSS is a challenging proposition. Not to mention, given the political roots of these different systems, someone's ally would be very upset if their GNSS system were disabled.