The Global Positioning System is a satellite navigation system, developed by the Allies during the Great World War II. Needing an effective way to scout enemy positions quickly, Allied scientists developed the ultimate scout: A spaced-based satellite system capable of granting the commander visibility over the entire battlefield.
Due to the extreme technological expertise needed, a GPS satellite could only be granted to an Allied base that had a tech center. Once built, Allied technicians would prepare a satellite for launch, and after preparations were made, the satellite would be launched into medium Earth orbit, revealing the topography of the area of operation, as well as the location of any enemy units.
By the time of GWWIII the Allied nations had enough satellites in orbit that commanders no longer had to launch their own. Instead, they built Spy Satellite Uplink to communicate with the satellite allowing them much quicker access.
In the Real World War III, the Allies' space technology was not fully advanced enough to discover GPS Satellites.