which the United States maintains diplomatic relations and with which the United States has an extradition treaty and the government of that country is in violation of the terms and conditions of the treaty. (c) Waiver The Secretary of State may waive the restriction under subsection (a) on a case-by-case basis if the Secretary certifies to the appropriate congressional committees that each waiver is important to the national interest of the United States. 21. Commercial leasing of defense articles Notwithstanding any other provision of law, and subject to the regular notification procedures of the Committees on Appropriations, the authority of section 23(a) of the Arms Export Control Act may be used to provide financing to Israel, Egypt, the North Atlantic Treaty Organization (NATO), and major non-NATO allies for the procurement by leasing (including leasing with an option to purchase) of defense articles from United States commercial suppliers, not including Major Defense Equipment (other than helicopters and other types of aircraft having possible civilian application), if the President determines that there are compelling foreign policy or national security reasons for those defense articles being provided by commercial lease rather than by government-to-government sale under such Act. 22. Special defense acquisition fund Not to exceed $900,000,000 may be obligated in any single fiscal year pursuant to section 51(c)(2) of the Arms Export Control Act for the purposes of the Special Defense Acquisition Fund (the Fund), to remain available for obligation until the end of the fiscal year in which it was obligated: Provided , That the provision of defense articles and defense services to foreign countries or international organizations from the Fund shall be subject to the concurrence of the Secretary of State. 23. Enterprise funds (a) Notification None of the funds made available under pursuant to an Act making appropriations for the Department of State, foreign operations, and related programs for bilateral