A claim under section 1645b of this title based upon an indirect ownership interest in a corporation, association, or other entity may be considered, subject to the other provisions of this subchapter, only if at least 25 per centum of the entire ownership interest thereof, at the time of such loss, was vested in nationals of the United States or if, at the time of the loss, nationals of the United States in fact controlled the corporation, association, or entity, as determined by the Commission.