A 30/06 can cover quite a distance and would be difficult to track from a long distance away. If they belong to the US government all they have to do is confirm it and tell the public to leave them alone instead of playing stupid guessing games what they like to do
I just loved that they went so far overboard in denying every reasonable theory about their origin that they created a vacuum in which it sounds like no one owns them. That opens up the logical conclusion that if they belong to no one, then no one should care if someone takes one down.
Of course, if that were to occur I guarantee we would know who they actually belong to when someone from that entity shows up at the amateur anti-aircraft gunner’s front door about five minutes later.