If a person, or a member of a controlled group (within the meaning of section
993
(a)(3)) which includes such person, participates in or cooperates with an international boycott during the taxable year (within the meaning of section
999
(b)), the amount of the credit allowable under section
901 to such person, or under section
902 or
960 to United States shareholders of such person, for foreign taxes paid during the taxable year shall be reduced by an amount equal to the product of—