Israel tested Stuxnet worm for effectiveness (NYTimes)

By William J. Broad, John Markoff and David E. Sanger, New York Times, January 15, 2011

The Dimona complex in the Negev desert is famous as the heavily guarded heart of Israel’s never-acknowledged nuclear arms program, where neat rows of factories make atomic fuel for the arsenal.
Over the past two years, according to intelligence and military experts familiar with its operations, Dimona has taken on a new, equally secret role — as a critical testing ground in a joint American and Israeli effort to undermine Iran’s efforts to make a bomb of its own.
Behind Dimona’s barbed wire, the experts say, Israel has spun nuclear centrifuges virtually identical to Iran’s at Natanz, where Iranian scientists are struggling to enrich uranium. They say Dimona tested the effectiveness of the Stuxnet computer worm, a destructive program that appears to have wiped out roughly a fifth of Iran’s nuclear centrifuges and helped delay, though not destroy, Tehran’s ability to make its first nuclear arms.
“To check out the worm, you have to know the machines,” said an American expert on nuclear intelligence. “The reason the worm has been effective is that the Israelis tried it out.”
Though American and Israeli officials refuse to talk publicly about what goes on at Dimona, the operations there, as well as related efforts in the United States, are among the newest and strongest clues suggesting that the virus was designed as an American-Israeli project to sabotage the Iranian program.
In recent days, the retiring chief of Israel’s Mossad intelligence agency, Meir Dagan, and Secretary of State Hillary Rodham Clinton separately announced that they believed Iran’s efforts had been set back by several years. Mrs. Clinton cited American-led sanctions, which have hurt Iran’s ability to buy components and do business around the world.
The gruff Mr. Dagan, whose organization has been accused by Iran of being behind the deaths of several Iranian scientists, told the Israeli Knesset in recent days that Iran had run into technological difficulties that could delay a bomb until 2015. That represented a sharp reversal from Israel’s long-held argument that Iran was on the cusp of success.
The biggest single factor in putting time on the nuclear clock appears to be Stuxnet, the most sophisticated cyberweapon ever deployed.