Except that it is completely a gimmick as espoused by Trump, who has no idea what he is talking about. The United States already as a “Space Force” in the United States Air Force Space Command (AFSPC) which is a major command under the United States Strategic Command (USSTRATCOM). There could be an argument made for moving AFSPC from under USSTRATCOM and into a Unified Combatant Command (UCC) directly within the DOD, since it actually was until 2002 where it was downgraded to a MAJCOM for reasons that have to do more with bureaucracy than practicality.
AFSPC is responsible for the ULA rocket missions which orbit all national security payloads, most NOAA and many NASA satellites, and most NASA interplanetary missions as well as maintaining orbital space awareness and tracking space hazards such as debris, charged particle belts, and solar weather events. AFSPC is already doing a fine job of this to the point of being a resource for many other allied and neutral nations, and while there has long been discussion about creating a “Space Force”, it is mostly by people disappointed that the Air Force found a crewed space program to be of little practical value with advances in satellite surveillance technology and cancelled the Manned Orbiting Laboratory and the X-20 “Dyna-Soar”, and only very reluctantly and expensively participated in the Space Transportation System (“Shuttle”) before the Challenger failure made it clear that it required alternative access to space.
The current GPS satellite constellation has 31 operation satellites in Medium Earth Orbit altitudes. With more than three satellites over the horizon, receivers can calculate a location on the surface of the Earth to within a few meters of precision, which is adequate for nearly every navigational purpose. Cutting down the constellation to the point that there were less than three satellites would require taking out nearly half of the standard 24 sat constellation an including birds that are in reserve, which is probably beyond the ASAT capabilities of any nation. More concerning are weather monitoring satellites which are aging without replacement, and the Milstar series. The military has been moving to commercial satellite communications for personnel usage, and those are at lower altitudes and not as well protected against both natural and hostile threats. A Carrington-type solar could potentially damage or disrupt many military satellites and potentially all commercial satellites in MEO or lower, which would hobble US and NATO response to any aggressive action by an adversary which is not as dependent upon satellites for communications and navigation.
The efforts at detecting nuclear detonations are now directed at non-radiative detection, largely because of how easy it is to test weapons underground where no direct radiation is evident. (Radioactive fallout may still be released depending on how far underground and how well protected it is, but not the X-rays from the event itself which are absorbed by the earth.)
Loran-C was never in wide use by the military and could be readily spoofed by an adversary.
Note that not all navigation systems rely upon GPS. ICBMs and SLBMs use inertial navigation (sometimes combined with astro-inertial navigation using stellar references to correct in mid-flight). Although GPS has become the standard method for land and sea navigation, commercial and military aircraft typically use a blended inertial-GPS solution (space-integrated GPS-INS or SIGI) because GPS coverage can sometimes be problematic when moving at aircraft speeds. While turning off the GPS solution would significantly degrade precision, the INS solution will still give enough accuracy to guide to an airport or other fixed destination/target.
Map and compass navigation is not that difficult to learn that by itself would pose a problem (especially with modern high precision maps developed with satellite imagery), but the combined lack of direct communications and precision location would certainly pose a significant challenge to modern combined-arms and close air support tactics. Nobody wants the airstrike they just called to come raining down upon them and you don’t want your top cover heading off thirty degrees off mark because they couldn’t make out directions.
Stranger