The Stuxnet worm was used in 2010 against a nuclear research facility in Iran. It targeted a specific industrial control system and was designed to alter the programmable logic controller used to closely manage Iran's nuclear enrichment program. The attack spread, infecting systems globally. The North American Electric Reliability Cooperation issued five mandatory standards and seven voluntary measures to ensure that Stuxnet does not impact power generation facilities. The majority of electric utilities that responded to the inquiry indicated that they were complying with five mandatory Stuxnet measures. Far fewer indicated that voluntary measures were being implemented. Increased personnel screening was being conducted and many utilities indicated that assessments were under way to identify critical assets, the report found.