The North Atlantic Treaty Organization or NATO is an intergovernmental military alliance based on the North Atlantic Treaty which was signed on 4 April 1949. The NATO headquarters are in Brussels, Belgium, and the organization constitutes a system of collective defence whereby its member states agree to mutual defense in response to an attack by any external party. For its first few years, NATO was not much more than a political association. However, the Korean War galvanized the member states, and an integrated military structure was built up under the direction of two U.S. supreme commanders. The first NATO Secretary General, Lord Ismay, famously stated the organization's goal was "to keep the Russians out, the Americans in, and the Germans down". Doubts over the strength of the relation