Misplaced Nukes

I got this story off CNN. Apparently about a month and a half ago, the US Air Force flew some cruise missiles from a site in North Dakota to Louisiana; however, they forgot to remove the nuclear warheads from the cruise missiles beforehand. Needless to say, this was a major screw up. After a six week investigation, several people have lost their jobs and others have been demoted. But how did this happen in the first place? What does it say about the efficacy of Homeland Security if we can't even keep track of our own nukes? How should the government react to such a slip-up, and how should we properly oversee dangerous weapons in the military?