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 any transfer authority provided herein is in addition to any other transfer authority provided by law: Provided further , That such amount is designated by the Congress as being for an emergency requirement pursuant to section 251(b)(2)(A)(i) of the Balanced Budget and Emergency Deficit Control Act of 1985. Procurement Shipbuilding and conversion, navy For an additional amount for Shipbuilding and Conversion, Navy , $2,155,000,000, to remain available until September 30, 2028, to support improvements to the submarine industrial base and for related expenses: Provided, That of the total amount provided under this heading in this division, funds shall be available as follows: Columbia Class Submarine (AP), $1,955,000,000