However, presidents have sometimes entered into executive agreements to achieve goals that would not have the support of two-thirds of the Senate. In the United States, executive agreements are binding internationally when negotiated and concluded under the authority of the president on foreign policy, commander-in-chief of the armed forces, or a previous act of Congress. For example, the president, as commander-in-chief, negotiates and enters into status of forces agreements (SOFAs) governing the treatment and disposition of U.S. armed forces stationed in other nations. However, the President may not unilaterally conclude executive agreements on matters not within his constitutional authority. In such cases, an agreement should take the form of an agreement between Congress and the executive or a contract with deliberation and approval by the Senate.