A computer virus (or more accurately, a worm) called Stuxnet has somehow infected the Iranian nuclear weapons program's computers. This is remarkable because the Iranians had apparently gone to extraordinary lengths to isolate their nuclear weapons development computer system from every other computer in the world; no hacker could have found a way in to that network from his living room in Yaroslavl or Philadelphia because there were no physical or ethernet connections between those computers and the internet. Yet somehow the virus got there.
And according to the Jersualem Post, this has set the Iranian nuclear weapons development program back by two solid years. Stuxnet has been as effective as an overt military strike against the weapons development program, and was somehow done without anyone firing a shot or anyone being killed.
No one will take credit for Stuxnet. There is speculation that it was developed by or at the behest of the Pentagon, or maybe by the Israeli Defense Forces, or who knows who else. But there is no doubt that Stuxnet was targeted directly at the Iranian nuclear program and whoever is responsible for it had conclusively demonstrated that the age of cyber-warfare is upon us.t