States, unless the Secretary of Defense certifies to the congressional defense committees that such an acquisition must be made in order to acquire capability for national security purposes that is not available from United States manufacturers. 8033. (a) The Secretary of Defense may, on a case-by-case basis, waive with respect to a foreign country each limitation on the procurement of defense items from foreign sources provided in law if the Secretary determines that the application of the limitation with respect to that country would invalidate cooperative programs entered into between the Department of Defense and the foreign country, or would invalidate reciprocal trade agreements for the procurement of defense items entered into under section 4851 of title 10, United States Code, and the country does not discriminate against the same or similar defense items produced in the United States for that country. (b) Subsection (a) applies with respect to— (1) contracts and subcontracts entered into on or after the date of the enactment of this Act