In September 2010, media reports emerged about a new form of cyber attack that appeared to target Iran, although the actual target, if any, is unknown. Through the use of thumb drives in computers that were not connected to the Internet, a malicious software program known as Stuxnet infected computer systems that were used to control the functioning of a nuclear power plant. Once inside the system, Stuxnet had the ability to degrade or destroy the software on which it operated. This book examines the discovery of the Stuxnet worm which has raised several issues for Congress, including the effect on national security, what the government's response should be, whether an international treaty to curb the use of malicious software is necessary, and how such a treaty could be implemented.