Sentinel ICBM Vertical Stacking Complete; Flight Testing on Track for 2027
Sentinel's readiness for flight test in 2027 anchors the Air Force's response to Russian modernization and Chinese ICBM growth—both documented in the prior coverage context as active threats. The program's on-time delivery now depends entirely on production ramp-up after Milestone B, not on hardware design. If the cost estimate at Milestone B exceeds budget authority, the Air Force will have to choose between accepting a smaller buy (fewer deployed missiles) or stretching the fielding timeline into the mid-2030s, both of which degrade the credibility of the deterrent against peer competitors already in the field.
Sentinel's vertical stacking clears the last integration hurdle before the first flight test, which means the Air Force's ICBM modernization timeline—the single most time-critical element of strategic deterrent recapitalization—is no longer at risk from hardware maturity delays.
The Milestone B gate by end of 2026 unlocks full-rate production authority and commits the FYDP to the early 2030s fielding target; missing that gate would force a two-year slip in initial operational capability. Watch the cost estimate at Milestone B: Gen. White's admission that "we don't think we're anywhere near a number right now" signals the program is still negotiating the production contract, and any overrun above the "realm of what we have talked about all along" will trigger a budget fight in the FY27 supplemental.
What is the actual unit cost estimate driving the Milestone B decision, and does it remain within the $100B+ range the Air Force cited in prior budget justifications?
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