Continued developments in science and technology have given small groups and even individuals the power to commit harm that historically only states could. But this decentralization of capability has also given nongovernmental groups and individuals the means to detect illicit and unsavory activities in ways that only state or international law enforcement, intelligence, and monitoring systems could, and these means, in many cases, exceed the capabilities that any but the largest countries and organizations had until recently. This session will explore the ability of scientists, engineers, and analysts, acting on their own or through nongovernmental (or non–security-related governmental) and civil society organizations, to observe or infer the existence of activities that threaten international security. How can technology and alert practitioners, ranging from seismologists to photo interpreters to data miners, supplement national and international law enforcement and intelligence systems to uncover threats to international security that others would prefer to keep hidden? How do these additional inputs complicate states’ efforts to monitor each other’s behavior?