39 U.S.C. § 406: Postal services at Armed Forces installations

The Postal Service may establish branch post offices at camps, posts, bases, or stations of the Armed Forces and at defense or other strategic installations. The Secretaries of Defense and Transportation shall make arrangements with the Postal Service to perform postal services through personnel designated by them at or through branch post offices established under subsection (a) of this section. are employed by the North Atlantic Treaty Organization; and perform functions in support of the Armed Forces of the United States; and in the best interests of the Department of Defense; and otherwise authorized by applicable host nation law or agreement. No funds may be obligated or expended to establish, maintain, or expand a post office established under subsection (a) for the purpose of use described in paragraph (1) of this subsection.