In any school feeding programs undertaken on and after September 27, 1962 outside the United States pursuant to section 1431 of this title, section 308 of Public Law 480 (83d Congress), as amended, and section 1431b of this title, the Secretary shall receive assurances satisfactory to him that, insofar as practicable, there will be student participation in the financing of such programs on the basis of ability to pay, and such programs shall be undertaken with the understanding that commodities will be available for those programs only in accordance with the provisions of such statutes and that commodities made available under section 1431 of this title will be available only in accordance with the priorities established in such section.