This book is an analysis of the threat of genetically modified organisms (GMOs) for biological warfare. Evaluating the potential threats posed by advances in biotechnology, especially genetically modified organisms (GMOs) and synthetic biology remains a contentious issue. Some believe that, inevitably, these advances will lead to a catastrophic biological attack. Others believe that, despite these advances, the scientific and technical requirements, as well as the fundamental laws of natural selection will prevent such an attack.To better understand this issue, this study narrowed the scope of consideration in several dimensions. First, our analysis primarily focused on what we defined as a "catastrophic biological attack", with a required level of damage more associated with biological warfare than bioterrorism. This damage would need to be direct in nature where the effect is more physical than psychological. Second, this biological attack would be restricted to the United States, not another nation or entity. In this sense, U.S. geography, climatology, infrastructure and medical systems play to counterbalance any potential biological attack. Even within a more narrow scope, there remains inherent complexity and uncertainty which, combined with the considerable rate of change for biotechnology, defies a simple, straightforward answer.We approached the issue by establishing an "Analytical Framework"--a baseline of the technical requirements to "play" in the field of GMOs at the scale of biological warfare. The primary focus of the framework are those aspects of the technology directly affecting humans by inducing virulent infectious disease, or through expression of toxins or suppression of the immune response of target subjects. Parallel threats exist for animals and plants in the food chain and, secondarily, in the ecosphere. Although not specifically included in this analysis, those threats can also be evaluated within the analytical framework.