Public government statements have cited cyberattacks by terrorists as a major concern for national security. To date, no large-scale cyber-terrorist attack has been observed, but terrorists are known to be using the Internet for various routine purposes. The discovery of Stuxnet in 2010 was a milestone in the arena of cybersecurity because, although a malware attack on industrial control systems was long believed to be theoretically possible, it was different to see malware used in reality to cause real physical damage. Stuxnet demonstrated that a sufficiently determined adversary with sufficient resources might be able to damage U.S. critical infrastructure physically through a cyber attack. Did Stuxnet change the threat of cyberterrorism?