It shall not be unlawful under this Chapter:
(1) To engage in conduct required by or expressly authorized by acts of the United States Congress, a United States treaty, a United States regulation, or a United States executive order;
(2) To enter into any agreement with an international organization entirely composed of member governments or their contracting representatives which requires that a preference or priority be given to the citizens or products of one or more of such member governments;
(3) To enter into any agreement with respect to the insuring, handling, or shipping of goods, or choice of carrier while in international transit.