Shortly after 911 military facilities were jamming GPS L1/L2 signals as a precaution to attack. I was using the same frequencies that the military uses and got jammed. I called the OD of the navy base and he said he didn't know anything about it. They don't advertise because it's a DoD system and they can do what they want with it. We're just lucky they've developed and broadcast an uncoded signal that civilians can use.
The uncoded signal may be getting jammed. That would be the one that some military like Iran could use if someone sold them a Garmin. It isn't a precise signal and can't be used for weapons guidance. Commercial aircraft are probably using authorized military coded signals but I wouldn't know that for a fact.
As far as an imminent attack on some poor country like Iran I doubt that it's a sign. The military has tested their local area jamming capability in the US before. It drives people crazy. Think ground assault.