N.D. Cent. Code § 28-06.2-01
Service must be made upon the United States by any person authorized to make service under state law or the rules of civil procedure by delivering a copy of the summons and of the complaint to the United States attorney for the federal judicial district in which the action is brought, or to an assistant United States attorney in that district, or to a clerical employee designated by the United States attorney, and by sending a copy of the summons and of the complaint by certified mail to the attorney general of the United States, at Washington, District of Columbia, and in any action attacking the validity of an order of an officer or agency of the United States not made a party, by also sending a copy of the summons and of the complaint by certified mail to such officer or agency.
N.D.C.C. § 28-06.2-01