There has been several people in the United States who have sucessfully designed a “private” atomic bomb using “off the shelf” parts.
To make the bomb they need sufficient materials of the right type which are not available to the common person. They need a delivery system and be able to burst it at altitude to really give it the large area effect... lots of variables. There have been many people to “claim” things and magazines that talk about that. I would give them little credibility.
These rouge nations however have the ability to actually build something, example North Korea (accomplished), Iran (trying)... they also have the ability to develop a delivery system ( http://en.wikipedia.org/wiki/Sina-1 ), that's why Iran put a satellite into orbit a while back (2005) and has been refining this technology concurrently with their development of “the bomb.” None of this is for civilian use, it's to develop a bomb and delivery system. That's why “Sputnik” was in reality the big deal it was. It wasn't just a symbolic thing where the Soviets had beaten us to the punch, it was their proclamation of the mastery of orbital mechanics. At that point they could target any spot on earth if they so chose. Notice/advanced warning time was reduced to 30 minutes, the ability to defend oneself reduced to near zero, every spot on the globe could be targeted.
The real threat is from abroad while our leaders stick their heads in the sand or even try to exploit these bad situations for some economic benefit (i.e. Iran who everyone is reluctant to stop trade with because of “money/oil”), all our so called leaders worry about is Bubba and how many shotguns he owns since these are the trendy media grabbing story lines that get lots of attention. In Germany they might chase you down if you have a swastika on a flag, as if that's the end of the world.
When we fail, when things are out of control, people and institutions tend to focus in on those things we have control over (The wife beater who feels out of control in the rest of his life does that). So enjoy your X-ray at the airport, watch the federal agents assigned to protect abortion clinics, and smile to the camera on every intersection while the real bad guys are out there are building a device capable of murdering entire cities at a time.
America under Obama has gone to her pre 911 mode regards national security.