This chapter introduces the book, defines key terms, reviews the literature, and describes the process of research. It also sets out the book's structure, and summarizes the argument, which is that Trump's War on Terror may, in many respects, not look different from the counter-terrorism campaigns of his predecessors, but that his counter-terrorism doctrine -- which can be summed up as "killing terrorists" and "keeping Muslims out of the country" -- is deeply at odds with established views of American values and America's role in the world. Since taking office, American counter-terrorism has become more militaristic and less interested in causes and consequences. Far-right extremists feel emboldened. The biggest shift, however, has been the systematic ideological conflation between terrorism, immigration, and Islam, which has undermined the idea of America as an ethnically and religiously diverse nation. Trump's War on Terror has not only made the world and America less safe, but weakened America's greatest soft power asset -- they very idea of America.