"The NSS establishes homeland security as the first priority of the Nation. The Armed Forces' role in homeland security is complex, combining actions overseas and at home to protect the United States. Our first line of defense is abroad and includes mutually supporting activities with US allies to counter threats close to their source. Closer to home, the Armed Forces use their capabilities to secure strategic air, land, sea and space approaches to the United States and its territory. When directed, the Armed Forces employ military capabilities at home to protect the nation, the domestic population and critical infrastructure from direct attack". (DOD/JCS, The NMS of the USA, 2004, 2).