RIP GPS? Russia Is Testing How It Can Jam NATO's Navigation Systems

Well to a large extent that seems to have been on the watch standers and the leadership who failed to properly train and supervise them. However I have a strong suspicion that the Navy team in the Gulf a couple of years ago had their GPS spoofed. They were likely over reliant upon it, "head in the cockpit" as it were, or they would have noticed something was off.

PO1 Kevin Dougherty - The obvious tactical application would be to make GPS guided munitions miss, making very expensive holes in the (wrong) ground.

That is one application, and one already in use in a number of places is spoofing to protect strategic locations etc. It is being done in Moscow, and the Black Sea, and there is evidence that it's being done in China to hide illegal shipments to and from NK and Iran. I suspect Iran has also used said technology against us on at least two occasions.

I suspect it would also have a significant degradation of our land force's abilities. first it would make siting of artillery less accurate, and hence targeting as well. I also suspect that like the Navy and celestial navigation, ground navigation has been allowed to atrophy, at least to some degree.

Yes and sadly terrestrial/celestial navigation seems to be minimal, if available at all in most of our service academies. The USCG was the only one that has been continuously teaching it. From what I understand, Annapolis has picked it back up, dunno about the others..