I think I read somewhere that the military is looking at creating non-GPS jam-proof navigation technology that involves a chip that contains multiple super accurate accelerometers. When the chip is manufactured it "knows" its current location, then by tracking acceleration in multiple directions it can calculate speed and direction ... constantly knowing where it is ... and even knowing relative position. Pretty cool idea.

I doubt that the US Govt would block GPS for all users across the country. but I am sure they would consider shutting it down at critical targets locations to protect things like the White House & Pentagon. That's logical. But they would need to know that an imminent threat exists ... that's their main headache.

Pete2