(3) The term “international organization” means the following: (A) A public international organization designated pursuant to section 1 of the International Organizations Immunities Act ( 59 Stat. 669 ; 22 U.S.C. 288 ) as being entitled to enjoy the privileges, exemptions, and immunities provided in such Act. (B) A public international organization created pursuant to a treaty or other international agreement as an instrument through or by which two or more foreign governments engage in some aspect of their conduct of international affairs. (C) An official mission, except a United States mission, to a public international organization referred to in subparagraph (A) or (B).