Stuxnet reportedly compromised Iranian PLCs, collecting information on industrial systems and causing the fast-spinning centrifuges to tear themselves apart. Exploiting four zero-day flaws, Stuxnet functions by targeting machines using the Microsoft Windows operating system and networks, then seeking out Siemens Step7 software. Stuxnet specifically targets programmable logic controllers (PLCs), which allow the automation of electromechanical processes such as those used to control machinery and industrial processes including gas centrifuges for separating nuclear material. Although neither country has openly admitted responsibility, the worm is widely understood to be a cyberweapon built jointly by the United States and Israel in a collaborative effort known as Operation Olympic Games. Stuxnet targets supervisory control and data acquisition ( SCADA) systems and is believed to be responsible for causing substantial damage to the nuclear program of Iran. Stuxnet is a malicious computer worm first uncovered in 2010 and thought to have been in development since at least 2005.