Obama on Iran

So let me get this straight, Iran is not a threat to the U.S.? Then, why is he going to waste his time meeting with the leader of a "tiny" country who is not a threat to us? And didn't we learn on 9/11 that it doesn't take massive amounts of money to inflict harm on us. Does Obama think that only countries (or groups) that spend more than "1/100th" of what we do on the military are threats to us? So Al Qaeda would therefore not be a threat to us? I'm confused.