I was also wondering: Why would the U.S. government admit to the existence of UFOs? After watching the film "Unacknowledged" with Steven M. Greer and considering my knowledge about False Flag Operations (like the Gulf of Tonkin Incidence, 1964) I think it might be part of the preparation to hoax an alien attack. It would mean the ultimate war and strengthen the military–industrial complex more than ever before. Who would care about minor inconveniences like dying bees or starving children, when we are attacked by aliens?
I strongly recommend watching the film if you are interested in this topic.