10 U.S.C. § 3803

Advance payments made under section 3801 of this title may be made only if the contractor gives adequate security and after a determination by the head of the agency that to do so would be in the public interest. Such security may be in the form of a lien in favor of the United States on the property contracted for, on the balance in an account in which such payments are deposited, and on such of the property acquired for performance of the contract as the parties may agree. This lien is paramount to any other liens and is effective immediately upon the first advancement of funds without filing, notice, or any other action by the United States.