The North Atlantic Treaty Organization, or NATO, was established by several western nations after World War II to create a collective security defense against Soviet aggression. Continuing long after the breakup of the Soviet Union, this peacetime military alliance has grown since its inception, now counting 30 member states from North America and Europe. Providing historical context and current examples, the viewpoints in this resource explore and debate NATO's relevance and effectiveness in a world vastly different than the one the organization was conceived in.