Stuxnet was a computer virus unleashed in 2009 that targeted Iran's nuclear facilities. It disrupted centrifuges used to enrich uranium, slowing Iran's nuclear program. The virus was introduced via USB and spread through industrial control systems. Stuxnet is believed to have been created by the U.S. and Israel to damage Iran's nuclear capabilities without using military force. It changed cyber security worldwide and highlighted the risks of cyber attacks targeting critical infrastructure.