Section 6446 - Effects on existing contractsThe President shall not be required to apply or maintain any Presidential action under this part-
(1) in the case of procurement of defense articles or defense services-(A) under existing contracts or subcontracts, including the exercise of options for production quantities, to satisfy requirements essential to the national security of the United States;(B) if the President determines in writing and so reports to Congress that the person or other entity to which the Presidential action would otherwise be applied is a sole source supplier of the defense articles or services, that the defense articles or services are essential, and that alternative sources are not readily or reasonably available; or(C) if the President determines in writing and so reports to Congress that such articles or services are essential to the national security under defense coproduction agreements; or(2) to products or services provided under contracts entered into before the date on which the President publishes his intention to take the Presidential action. Pub. L. 105-292, §406, 112 Stat. 2808.