The Iranian authorities must have known this, yet they allowed a civilian aircraft to overfly a live firing zone.
Which authorities would that be? The aircraft was a civilian airliner, flying under civil ATC on an established civil airway, on a normal scheduled flight, in peacetime. The whole airspace around the area is busy with civil traffic. One would imagine that great care would be taken by the military to avoid civil aircraft - including the huge number of American citizens that are normally aboard airliners flying over the Gulf at any time of the day or night.
In fact, at that time civil airliners were often aggressively addressed by US naval forces on 121.5 but not all civil airliners have the triple VHF installation needed to monitor guard while working the ATC frequencies during aproach in such a busy ATC environmment. The third VHF is not required for "full airways fit" under Part K. Even with three VHFs, many aircraft are using the third for its intended purpose of downloading ACARS data to the destination station. The civil ATC frequencies are openly published and available on all airways charts. Why did the military choose not to use them, but try to use 121.5 instead? Anybody here know?