There is a new system in the works by the europeans, Galileo. It is
supposed to be independent of military control so you won't see threats
of system shutdown. I'm sure the pentagon is working out how to jam it,
etc.

http://www.esa.int/export/esaNA/GGGM...C_index_0.html
http://www.eubusiness.com/press/EUPress.2003-12-22.1818

Let the cat'n'mouse games continue. In previous centuries road signs
were moved around and fake maps made to confuse the enemy, I doubt that
has happened in a while. But the stakes are always getting higher, no
one died as a direct result of a sign movement (the guys with guns
lying in ambush on the other hand...)

-lance smith