USN is a possible theory but the thing that troubles me about that is that how would it ever be kept secret after so long and so many people aware of the truth ?
Have we ever estimated how many sailors would have had to keep quiet about this?
While we know the Navy was in the vicinity, do we know how many ships? How many crew?
Would everyone have known if there was an accidental missile launch, just the immediate team involved, or some intermediate players (radar)?
If there was a secrecy order, would it still be effective? Would the penalty for violation still be a deterrent - some of those sailors might be pretty old by now.
Would a secrecy order be available under a FOIA?