Stuxnet

A computer worm or bot reported to have been created by the United States Government (probably the National Security Administration) in conjunction with Israel, its initial purpose was to infiltrate the computers at Iran's nuclear refinement facility and allow the U.S. a way to disable or damage Iran's centrifuges. The program "Olympic Games" was initiated by George W. Bush in 2006 and continued by Barack Obama even after the worm went "rogue" and infected computers in other countries.
After the worm was secretly introduced into the nuclear facility's computers, about 1,000 of 5,000 centrifuges were damaged or destroyed by commands to over-speed. More damage was also caused to control mechanisms and monitors. According to some, citing United Nations conventions, this puts the United States technically at war with Iran.