US President on Wednesday 21st March 2012, joked about the theories of aliens landing in Roswell in 1947, during a visit.

"I announced to people when I landed that I come in peace,... Let me tell you, there are nine- and 10-year-old boys... when I meet them they ask me, have you been to Roswell, and is it true what they say? And I tell them, If I told you I'd have to kill you. And you know, their eyes get all big,... so we are gonna keep our secrets here"...