Not sure why we need our own though - what with GPS, GLONASS and Galileo i would have thought that there was plenty commercially available for anyone.
Nor me, heck I use a GPS as an end-user, supposed to have GPS+GLONASS for improved accuracy, turn off GLONASS (Russian) whether in Moscow, half-way across Uzbekistan or somewhere else in SE Asia to see the difference and it still works just as accurately...
I'm not sure coverage is extended or accuracy (around 5 metres) whether I had one, both switched on, everything seemed exactly the same....
Now Satphone coverage (Voice+Data) are a different matter.... I can well understand the rationale behind adding a few sats for national Security.