until September 30, 2026, may be transferred to accounts under the headings Operation and Maintenance , Procurement , Research, Development, Test and Evaluation , and Revolving and Management Funds for replacement, through new procurement or repair of existing unserviceable equipment, of defense articles from the stocks of the Department of Defense, and for reimbursement for defense services of the Department of Defense and military education and training, provided to the government of Ukraine or to foreign countries that have provided support to Ukraine at the request of the United States: Provided further , That amounts made available under this heading may also be transferred to accounts under the heading Procurement for expansion of public and private plants, including the land necessary therefor, and procurement and installation of equipment, appliances, and machine tools in such plants, for the purpose of increasing production of critical munitions: Provided further , That funds transferred pursuant to a transfer authority provided under this heading shall be merged with and available for the same purposes and for the same time period as the appropriations to which the funds are transferred: Provided further , That the Secretary of Defense shall notify the Congressional defense committees of the details of such transfers not less than 15 days before any such transfer: Provided further , That upon a determination that all or part of the funds transferred from this appropriation are not necessary for the purposes provided herein, such amounts may be transferred back and merged with this appropriation: Provided further , That up to $4,000,000,000 of the funds made available under this heading may be transferred between the Ukraine Security Assistance Initiative and the funds provided for the replacement of defense articles: Provided further , That transfer authority provided under this heading is in addition to any other transfer authority provided by law: Provided further , That such amount is designated by