Air Force wanted it to go away. Would not accept the conclusions of lower-level officers that we were being visited by extra-terestrials.
By 1952 there was an enormous wave of sightings, focussed on Washington D.C.
Three radars were picking up targets in D.C. (I am not sure whether to believe this or not...they aren't sourcing this very well.)
There was a guy on Art Bell's show one night (maybe someone else knows his name) that claims that the government confirmed that there were UFOs and extraterrestial beings in the 1950s. He's got quite a story that includes it going all the way to Eisenhower who determined that the US government could not confirm their existence without threatening our entire culture, values and beliefs. Now, I'm not saying I agree with this but at worse it's a really good science fiction story :)