The level of threat posed by a terrorist group is determined in large part by its ability to build its organizational capabilities and bring those capabilities to bear in violent action. As part of homeland security efforts, technology systems play a key role within a larger, integrated strategy to target groups' efforts and protect the public from the threat of terrorist violence. Terrorist organizations are acutely aware of government efforts to deploy these systems and actively seek ways to evade or counteract them. This study draws on relevant data from the history of a variety of terrorist conflicts to understand terrorists' countertechnology efforts. Depending on the adaptive capabilities of the adversary, a defensive model built on a variety of security measures that can be adjusted and redeployed as their vulnerable points are discovered provides a superior approach to addressing this portion of terrorist behavior. Fully exploring adversaries' countertechnology behaviors can expose vulnerabilities in U.S. defenses and help the nation make the best choices to protect it from the threat of terrorism. Read Less