25 U.S.C. § 47a

The Secretary, in his discretion, may require security other than bonds required by sections 3131 and 3133 of title 40 when entering into a contract with an Indian-owned economic enterprise pursuant to the provisions of the Act of June 25, 1910 (25 U.S.C. 47), for the construction, alteration, or repair of any public work of the United States: Provided, That, the alternative form of security provides the United States with adequate security for performance and payment.