Anybody who is in the unfortunate position of deciding whether the target they’re aiming at is a missile or passenger plane needs to do the following simple calculus: if you are even slightly unsure, don’t do anything (especially if the object is not even threatening your life). If it turned out to be a hostile missile, your country then goes on the offensive against whoever fired it and it’s just another attack. No one is going to come after you for being cautious (maybe you get dishonorably discharged but that’s it). But if you go the other way and accidentally take down a passenger jet, not only do you kill a bunch of innocent people, the international community will be out for your blood.