[Rokke]

"If Iran is spoofing GPS signals in order to lure us into a trap just across the real territorial line,"

In order to jam or "spoof" GPS signals, you need to be between the satellites and the receiver. Because receivers rely on signals from several different satellites to compute a solution, you need a jammer very close (and above) the receiver being jammed. In short, Iran is not having any influence on our GPS systems.

[Rokke]

I should add, this applies to military grade receivers more so than civilian systems, which are far less robust and much more susceptible to noise.

[Southack]

"In order to jam or "spoof" GPS signals, you need to be between the satellites and the receiver. Because receivers rely on signals from several different satellites to compute a solution, you need a jammer very close (and above) the receiver being jammed. In short, Iran is not having any influence on our GPS systems." - Rokke

With all due respect, you just need a more powerful signal, which is easily done from the ground.

Even if Iran had to be in the skies to do it, they could use a UAV, purpose-built aircraft, or balloon...but a ground transmitter should easily be able to overwhelm a sat signal making those steps perhaps superfluous.