What is the role of the joint cheifs of staff?

Responsibilities as members of the Joint Chiefs of Staff take precedence over duties as the Chiefs of Military Services. The Chairman of the Joint Chiefs of Staff is the principal military adviser to the President, Secretary of Defense, and the National Security Council (NSC), however, all JCS members are by law military advisers, and they may respond to a request or voluntarily submit, through the Chairman, advice or opinions to the President, the Secretary of Defense, or NSC. I hope this helps

Americans agreed to the settlement terms established by the mexican government.