The Secretary of Defense (or Secretary of a military department) may not lease to a non-Federal agency in the United States any aircraft or vehicle owned or operated by the Department of Defense if suitable aircraft or vehicles are commercially available in the private sector. However, nothing in the preceding sentence shall affect authorized and established procedures for the sale of surplus aircraft or vehicles.
10 U.S. Code § 2560 - Aircraft and vehicles: limitation on leasing to non-Federal agencies
Provisions similar to those in this section were contained in Pub. L. 101–165, title IX, § 9025, Nov. 21, 1989, 103 Stat. 1134, which was set out as a note under section 2241 of this title, prior to repeal by Pub. L. 101–510, § 1481(g)(4).