The program to develop a reentry vehicle that can deliver the future W87-1 warhead from the Ground Based Strategic Deterrent -- the Air Force's next intercontinental ballistic missile system -- is expected to reach a key early milestone in the beginning of the next calendar year. The Mk21A reentry vehicle program is moving toward a system requirements review during the second quarter of fiscal year 2020, Leah Bryant, an Air Force spokeswoman, told Inside Defense in an Oct. 22...