Modern terrorists, especially jihadist groups, use the Internet for propaganda, recruitment, psychological warfare, planning and coordination, fund-raising, and obtaining information on potential targets. This article’s proposed strategy for disrupting terrorists’ online activities involves the use of “noise.” In communication theory, “noise” is the term used for any feature in the communication process that obstructs, corrupts, or distorts the message being sent. The use of “noise” in countering terrorists’ communications on the Internet involves harming the flow, the decoding, the communicator’s credibility and reputation, the signal’s clarity, the channel’s reach, and the receivers’ trust. Creating and using semantic, psychological, cultural, and physical “noises” describes a variety of countermeasures that can be organized in a strategic framework that undermines terrorist objectives in using the Internet. After discussing this concept of “noise” in communication processes, this article identifies the vulnerabilities of terrorist online activity and discusses how various features of “noise” can be organized into a strategy for countering online terrorist activities. The proposed strategy involves the technological disruption of the flow of terrorist online communications by damaging their Web sites, the redirection of users to spreading “viruses” and “worms,” blocking access, hacking, and total destruction. Counterterrorism “noise” can also have psychological/social features that involve counter-propaganda designed to modify the attitudes, perceptions, and behaviors of the target audiences for terrorists’ online communication strategies. 1 figure and 49 notes