If you were skimming the news this morning, we could understand why you might be confused and thinking that the hacking collective Anonymous has access to real U.S. warheads. Stop worrying, they don't.
They allege they do have sensitive information about the Justice Department, though. The group took over the United States Sentencing Service website early Saturday. The site has been taken down now, but The Verge pointed out you can still see the defaced-by-Anonymous version through this Google cache.
According to the lengthy note left on the site, the attack was carried out in the name of Aaron Swartz, the hacker and activist who committed suicide two weeks ago.