Payment of any award made pursuant to section 1641b or 1641d of this title shall not, unless such payment is for the full amount of the claim, as determined by the Commission to be valid, with respect to which the award is made, extinguish such claim, or be construed to have divested any claimant, or the United States on his behalf, of any rights against the appropriate foreign government or national for the unpaid balance of his claim or for restitution of his property. All awards or payments made pursuant to this subchapter shall be without prejudice to the claims of the United States against any foreign government.