If, within one hundred and eighty days after the first session scheduled by the Mediator under section
640d–1
(c) of this title, full agreement is reached, such agreement shall be put in such form as the Mediator determines best expresses the intent of the tribes and shall then be submitted to the Secretary and the Attorney General of the United States for their comments as they relate to the interest of the United States in the proceedings. These comments are to be submitted to the Mediator and the negotiating teams within thirty days. The negotiating teams and the Mediator shall then consider the comments and, if agreement can still be reached on terms acceptable to the negotiating teams and the Mediator within sixty days of receipt by him of the comments, the agreement shall be put in final written form and shall be signed by the members of the negotiating teams and the Mediator. The Mediator shall then cause the agreement to be entered into the records of the supplemental proceedings in the Healing case. The provisions of the agreement shall be reviewed by the District Court, modified where necessary, and put into effect immediately thereafter.