; and (B) by striking the milestone decision authority for the major defense acquisition program approves a program that and inserting the program ; and (2) by striking subsection (b). 832. Implementation of recommendations of the Independent Study on Consideration of Sustainment in Weapons Systems Life Cycle (a) Implementation required Not later than 18 months after the date of the enactment of this Act, the Secretary of Defense shall, except as provided under subsection (b), commence implementation of each recommendation submitted as part of the independent assessment produced under section 844 of the National Defense Authorization Act for Fiscal Year 2017 ( Public Law 114–328 ; 130 Stat. 2290). (b) Exceptions (1) Delayed implementation The Secretary of Defense may commence implementation of a recommendation described under subsection (a) later than the date required under such subsection if the Secretary provides the congressional defense committees with a specific justification for the delay in implementation of such recommendation. (2) Nonimplementation The Secretary of Defense may opt not to implement a recommendation described under subsection (a) if the Secretary provides to the congressional defense committees— (A) the reasons for the decision not to implement the recommendation; and (B) a summary of the alternative actions the Secretary plans to take to address the purposes underlying the recommendation. (c) Implementation plans For each recommendation that the Secretary is implementing, or that the Secretary plans to implement, the Secretary shall submit to the congressional defense committees— (1) a summary of actions that have been taken to implement the recommendation