Quote Originally Posted by Sigurd View Post
I haven't read all posts in this thread, but I felt I had to comment on the general topic.

First and foremost the NAVSTAR GPS is an American Military system. This normally means the US military use it during military campaigns.
Having worked in Navy intelligence, I have learned that The US military has GPS jamming capability.
(We, as in the Norwegian Military, tested such a jamming system)
There is also implemented in the GPS; forced inaccuracies that can be turned off with a flip of a switch.
This is problematic as satnav programmers must implement offset algorithms to the GPS softwares and build land based correction bases for them to show true positioning which even then leads to inaccuracies.
The US military during their military campaigns will turn off this offset and most Satnavs will be useless as The Gulf War I painfully demonstrated.
In Europe, satnavs showed boats running on the shore during the Gulf War.

This might sound like a conspiracy theory but my info comes from navigation system developers working in development of Military navigation systems in Norway.
first logical reason i have heard in support of an alternative GPS.

though in reality all GPS systems will be turnable off in the event of war, no great power will leave on a service that guides cruise missiles and tank brigades in the heart of its cities.