The Secretary of Agriculture with respect to National Forest System lands and the Secretary of a military department with respect to lands under the control of the military department which lie within or adjacent to the exterior boundaries of a unit of the National Forest System are authorized, subject to any applicable provisions of the Federal Property and Administrative Services Act of 1949, as amended, to interchange such lands, or any part thereof, without reimbursement or transfer of funds whenever they shall determine that such interchange will facilitate land management and will provide maximum use thereof for authorized purposes: Provided, That no such interchange of lands shall become effective until forty-five days (counting only days occurring during any regular or special session of the Congress) after the submission to the Congress by the respective Secretaries of notice of intention to make the interchange.