That would be the simplest explanation. Given the huge amount of money spent on US military, the value of having advanced military aircraft in their inventory,

That would be the simplest explanation. Given the huge amount of money spent on US military, the value of having advanced military aircraft in their inventory, and the desire to keep the technology secret and out of enemy hands - military based UFOs seems like a reasonable conclusion. The fact that the aircraft is moving at G forces unsustainable by biological life isn't surprising either given advances in drone tech. It would also make sense to shut the UFO program down as well if it was ending up with these secret programs getting accidentally revealed.