; (B) in the case of a letter of request for a defined-order letter of offer and acceptance or associated amendments and modifications, not later than 100 days after such date; and (C) in the case of a letter of request for a defined-order letter of offer and acceptance or associated amendments that involve extenuating factors, as approved by the Director of the Defense Security Cooperation Agency, not later than 150 days after such date. (3) Waiver The Secretary of Defense may waive paragraphs (1) and (2) if— (A) such a waiver is in the national security interests of the United States; and (B) not later than 5 days after exercising such waiver authority, the Secretary provides to the Committee on Foreign Relations of the Senate and the Committee on Foreign Affairs of the House of Representatives notice of the exercise of such authority, including an explanation of the one or more reasons for failing to meet the applicable deadline. (b) Expansion of country prioritization With respect to foreign military sales to member countries of the North Atlantic Treaty Organization, major non-NATO allies, major defense partners, and major security partners, the Secretary of Defense may assign a Defense Priorities and Allocations System order rating of DX (within the meaning of section 700.11 of title 15, Code of Federal Regulations (as in effect on the date of the enactment of this Act)). (c) Definitions In this section: (1) Blanket-order letter of offer and acceptance The term blanket-order letter of offer and acceptance means an agreement between an eligible foreign purchaser and the United States Government for a specific category of items or services (including training) that— (A) does not include a definitive listing of items or quantities