If anyone ever thought that the US can ever afford to turn off GPS, they are horribly mistaken.

"Businesses using it for navigation" isn't as trivial a thing as it sounds. Those "businesses" are airlines an other air carriers, and "navigation" is actually "getting on the ground without crashing."

GPS systems are already approved for flight in instrument conditions (i.e. zero visibility), including approaches to land. Furthermore, the FAA has announced that it is slowly phasing out its ground-based navigation systems (VORs and NDBs) and replacing it with GPS. While the ground-based systems will probably never be completely gone, GPS is becoming increasingly important for keeping planes on course and out of the trees.

Disabling (or even rendering less effective) civilian GPS systems would mean potentially crashing US civilian aircraft. It'd be like 9/11 all over again, except this time the government would be directly (and verifiably) responsible. No US president would dare authorize such a course of action without some serious advance notice to the nation to avoid disaster.

And if the US is faced with a crisis of such magnitude that that it would put such an operation into effect, it could just as easily add "shoot down N of the Galileo satellites" to the TODO list.