The announcement came less than a year after Iranian nuclear facilities were attacked . At the time a new worm appeared to be on Iran 's nuclear production capability . It was apparently designed to secretly infiltrate the centrifuge machines that refine uranium and make them spin so fast they would break , according to David Albright of the Institute for Science and International Security . `` About 10 % of the centrifuges were destroyed by Stuxnet , '' he said , which resulted in a setback for the Iranian nuclear program by as much as a year . The announcement left unclear which facilities are targeted by the new worm .
The announcement came less than a year after Iranian nuclear facilities were attacked . At the time a new worm appeared to be on Iran 's nuclear production capability . The announcement left unclear which facilities are targeted by the new worm .