Who, or maybe WHAT is behind the Stuxnet worm?

blogs.computerworld.com — Stuxnet, the most sophisticated malware ever, is shrouded in mystery. As if it were a sci-fi movie plot, conspiracy theories include Big Brother, psychic spies, UFOs, and one extraterrestrial cyber-worm. Sep 29, 2010 View in Crawl 4

Who, or maybe WHAT is behind the Stuxnet worm?