10 U.S.C. § 7062: Policy; composition; organized peace establishment

preserving the peace and security, and providing for the defense, of the United States, the Commonwealths and possessions, and any areas occupied by the United States; supporting the national policies; implementing the national objectives; and overcoming any nations responsible for aggressive acts that imperil the peace and security of the United States. In general, the Army, within the Department of the Army, includes land combat and service forces and such aviation and water transport as may be organic therein. It shall be organized, trained, and equipped primarily for prompt and sustained combat incident to operations on land. It is responsible for the preparation of land forces necessary for the effective prosecution of war except as otherwise assigned and, in accordance with integrated joint mobilization plans, for the expansion of the peacetime components of the Army to meet the needs of war. the Regular Army, the Army National Guard of the United States, the Army National Guard while in the service of the United States and the Army Reserve; and all persons appointed or enlisted in, or conscripted into, the Army without component. military organizations of the Army with their installations and supporting and auxiliary elements, including combat, training, administrative, and logistic elements; and members of the Army, including those not assigned to units;