The REAL Reason U.S. Does Not Shoot Down UFOS-- FEAR

For years, unidentified aircraft have been intruding on U.S. airspace, even swarming our multi-billion dollar warships.  The U.S. does not shoot them down because they know these flying objects are neither China', Russia's, nor ours.   So what does that leave?   The alternative is so unnerving that not even the Pentagon has the cojones to say it out loud.  Their actions have shown that they at least do believe these craft to represent technologically-advanced civilizations from another realm,  for which they are 

powerless to do anything about.