This protocol is apart of the GPS constellation put up by NATO countries. During times of aerial warfare the GPS system is designed to restrict access to non IFF (Identify: Friend/Foe) transponder equipped aircraft.

The tech is like this to deny foreign air forces from utilizing GPS in USA +NATO air spaces.
The company that maintains the majority of GPS in space is called Navstar. Great article from ScientificAmerican about this system from 2016.