NATO (Scotland says "Yes")

The North Atlantic Treaty Organization (NATO; pronounced /ˈneɪtoʊ/, NAY-toe); French: Organisation du traité de l'Atlantique Nord (OTAN)) Russian: Северо-Атлантический Союз, also called "the (North) Atlantic Alliance", is an intergovernmental military alliance based on the North Atlantic Treaty which was signed on April 4, 1949. The NATO headquarters are in Brussels, Belgium, and the organization constitutes a system of collective defense whereby its member states agree to mutual defense in response to an attack by any external party.