LGM-35A Sentinel

01 / Program record

The original promise survives the reset

Sentinel, formerly Ground Based Strategic Deterrent (GBSD), is a replacement program for the Minuteman III system and its supporting infrastructure—not simply a purchase of missile bodies. The September 2020 acquisition baseline preserved in the MSAR planned 659 end items: 25 development and 634 procurement. That accounting quantity is not a count of deployed or operational missiles. N01 · p. 13

The original objective and threshold are different. So is the MSAR's May 2029 forecast: it was an estimate, not the original June 2029 commitment. The report explicitly says its schedule estimates were under review. This edition does not promote those stale estimates into a current schedule or assign an exact month to “early 2030s.” Nor does it equate that announced initial-capability target with a documented, unchanged definition of formal IOC. N01 · p. 11, N04, N05

The Air Force notified Congress of a critical unit-cost breach on January 18, 2024. In July, DoD certified that the program met the criteria to continue, rescinded Milestone B and directed restructuring. These were consequential management decisions, not operational milestones. In February 2026 the Air Force targeted a new Milestone B decision by year-end; GAO's July publication still described evolving estimates. A subsequently signed replacement baseline was not established in this review. N02, N03 · p. 92, N04

A date discrepancy is retained, not silently repaired. The MSAR's history gives September 4, 2020 for Milestone B, its schedule table records September 1, and GAO uses a September 15 development-start reference for its practices assessment. The baseline table is explicitly dated September 4; the timeline uses September 2020. None of these day labels changes the June 2029 original IOC objective. N01 · pp. 9, 11, N03 · p. 91

“First flight” changed scope

GAO's February snapshot preserved a March 2028 first-flight plan. Its later annual assessment explains that the revised 2027 plan uses an above-ground launch pad with a reduced initial test scope; the first silo-based flight is instead targeted for Q3 FY2030 (April–June 2030). These are not like-for-like dates for the same test. Earlier learning may be useful, but moving one event forward is not proof that the original full-system milestone has recovered. The September announcement still described flight testing as future work. N12 · p. 1, N03 · p. 92, N05

02 / Program record

A dated program history

Actual entries identify what was reported: an award, a decision, a construction start or a test-related event. Publication dates are labeled where the precise event day is unavailable. A publication containing a forecast is not an achieved forecast.

1. Sep 2020Baseline

   Original commitment

   Original development commitment

   The September 2020 baseline set June 2029 IOC and a June 2030 threshold. Month precision avoids conflicting day fields in later reports. N01

2. Sep 8, 2020Contract

   Reported event

   Development contract awarded

   $13.293562839bn award; $85m obligated at award. Neither is total lifetime program spending. N07

3. Dec 11, 2023Reset

   Reported event

   Program deviation report signed

   Cost and schedule deviations were formally reported. The original baseline remained visible. N01

4. Jan 18, 2024Reset

   Reported event

   Critical cost breach notified to Congress

   The notification triggered the review. Its initial percentages differ slightly from the later budget-index-adjusted figures. N01

5. Jul 8, 2024Reset

   Reported event

   Continuation certified; Milestone B rescinded

   DoD announced the continuation decision and ordered restructuring. Certification was not delivery or approval of a final replacement baseline. N02

6. Feb 17, 2026Plan

   Reported event

   Air Force publishes reset targets

   End-2026 Milestone B and early-2030s initial capability remain announced plans, not achieved milestones. N04

7. Mar 27, 2026Construction

   Reported event

   Silo prototype groundbreaking reported

   Reported by this publication date; no exact groundbreaking day is assigned. Prototype work does not establish completed operational facilities. N09

8. Jun 10, 2026Contract

   Reported event

   Training facility contract awarded

   $113.852388m award and reported obligation for a facility, not an operational missile. N08

9. Jun 24, 2026Construction

   Reported event

   Utility-corridor pilot breaks ground

   Event reported in July; construction beginning is not network completion. N10

10. Jul 2, 2026Oversight

    Reported event

    GAO explains the changed flight-test plan

    The 2027 pad-based target and FY2030 silo-based target are different test scopes. This is the report's publication date. N03

11. Aug 17, 2026Construction

    Reported event

    Training-unit groundbreaking

    September 1 reporting describes an August 17 event and an early-2030s facility opening target. N11

12. Sep 14, 2026Test

    Reported event

    Inert assembly milestone reported

    The Air Force reports completed inert vertical assembly and a first-flight-specific review. No flight or IOC is established by this receipt. N05

13. End 2026Plan

    Forecast

    New Milestone B target

    A planned decision, not a signed decision established in this edition. N04

14. 2027Test

    Forecast

    Pad-based first-flight target

    Different scope from the previously described silo-based first flight; not an achieved flight. N03

15. FY2030 Q3Test

    Forecast

    Silo-based first-flight target

    April–June 2030 in the U.S. fiscal calendar; not the early-2030s initial-capability target. N03

16. Early 2030sPlan

    Forecast

    Initial-capability target

    Broad planning window; do not assign a precise replacement IOC date or month-delay statistic. N05

03 / Program record

The cost increase that can be compared

The MSAR supplies a reproducible historical, same-dollar comparison: the September 2020 baseline of $77.7407 billion versus a $106.4269 billion pre-recertification estimate, both in constant FY2020 dollars and both covering 659 end items. That is $28.6862 billion, or 36.90%, higher. This is the PB2025 estimate in a report labeled December 2023—not a newly approved 2026 cost estimate. N01 · pp. 13, 16

Military construction accounts for about 42.0% of that historical increase: $12.0458 billion of $28.6862 billion. This is arithmetic from the four reported cost categories, not a causal attribution of overruns. The military-construction account also is not identical to the broader command-and-launch segment identified in the later review. Source values, units and calculations are available in the downloadable data. N01 · p. 13, N02

Why the later $140.9 billion is shown separately

The July 2024 announcement reported a $140.9 billion CAPE acquisition estimate for a modified program and described it as 81% above the previous Milestone B estimate. We preserve those as DoD's reported figures. The release does not explicitly state their dollar basis; this edition does not independently harmonize them with the MSAR's constant-2020 or then-year series. The MSAR's separate $152.413 billion then-year estimate therefore cannot be placed against $140.9 billion and labeled a saving. N02, N01 · p. 13

GAO's 2026 assessment marks its current cost row under review, and says the reliability of the preliminary reset estimates remains unclear until the process and new Milestone B are completed. Missing final estimates are not zero. All these numbers are acquisition estimates—not cash spent, a lifetime sustainment bill, or a price per deployed missile. N03 · pp. 91–92

Selected funding, with its stage attached

These rows cover only Air Force RDT&E account 3600F, PE 0605238F, GBSD EMD. The FY2026 displayed total is the sum of discretionary enacted funding and the P.L. 119-21 spend-plan component; it is not a third pot to add again. FY2025 “Actuals” is the budget exhibit's total-obligational-authority presentation, not a transaction-level outlay measure. FY2027 is a request. Military construction, other accounts and Minuteman III sustainment are not silently folded into this selected line. N06 · printed p. 42

The historical MSAR funding summary labels its full $152.413 billion estimated acquisition appropriations as appropriated to date, or 100%, while separately reporting $8.8989 billion of expenditures. That internally awkward summary is not used here as verified congressional funding completion or a reconciled cash ledger. The dated, account-specific records above support a narrower claim. N01 · pp. 13, 24

04 / Program record

Contracts are not the program's price tag

The $13.293562839 billion development award and its $85 million initial obligation describe different stages of the same action. The original contract was cost-plus-incentive-fee, not a fixed-price guarantee that development could never cost more. The later MSAR lists a historical $13.3163 billion target and different contractor/program-manager estimates at completion while warning that replanning limited the earned-value figures. None is another purchase to add to the initial award. No current aggregate contract balance is asserted here. N07, N01 · pp. 21–22

The 2026 $113.852388 million training-facility award illustrates a separate construction commitment with the same amount reported obligated at award. It uses FY2025 funds despite the June 2026 award date. Its March 6, 2029 estimated contract completion differs from the Air Force's later early-2030s facility opening target. Construction completion and operational opening may cover different work; the reviewed evidence does not reconcile the dates or establish a contract extension. N08, N11

These are selected actions, not all prime contracts, modifications, subcontracts or obligations. They are not summed into a total-program spending claim.

05 / Program record

What has actually happened

The distinction is not “nothing has happened.” Documented development and construction work are real results. The question is which promise each receipt can close. An inert article assembled on a test pad does not close a flight-test or operational-capability commitment. A first-flight-specific design review does not establish that the entire system's original critical design review is complete. A groundbreaking does not close a facility-delivery commitment. N03, N05, N09, N10, N11

These are agency-reported events. Program Receipts has not independently observed the tests or certified effectiveness, nuclear readiness or the eventual completion cost.

06 / Program record

What would close the open questions

For a later edition, the most informative receipts would be:

1. A signed replacement baseline: approved cost, price basis, quantity, scope and schedule—not another broad target.
2. A flight-test result with its scope identified: distinguish pad-based development testing from the later silo-based event and operational evaluation.
3. A defined initial-capability declaration: specify what was delivered and accepted, not just a date window.
4. A reconciled funding trail: account-specific appropriations, obligations and outlays without overlapping totals or estimates.
5. A credible transition record: align Sentinel fielding with continued Minuteman III support. GAO identified transition-planning risks; that is not a finding in this edition that an actual readiness gap has occurred. N12 · p. 2

Bottom line: the selected record supports real progress and continuing uncertainty at the same time. The original June 2029 commitment remains the reference; the reset is not itself delivery, and the reviewed evidence cannot yet settle the final price or date. N01, N02, N03, N05

07 / Program record

How to read this edition

This is a finite public-record research edition, not comprehensive monitoring. Cost calculations use the explicitly labeled historical constant-FY2020 series; the newer unharmonized estimate is kept separate. Funding units were converted from thousands to millions without changing fiscal stage. No precise slip is calculated from an “early 2030s” range. Unknown current quantities, obligations, outlays and achieved IOC remain null in the data.

The official MSAR and GAO annual report were re-reviewed from hash-checked September 12 receipts after fresh access failed. The R-1 was freshly downloaded; official web articles were reviewed through indexed full-article retrieval where direct access was blocked. A source hash identifies a version, not its truth. Research, writing and verification were performed with AI assistance; arithmetic, source-table, link, browser and print checks are not independent human peer review.

All substantive content and references are available without JavaScript. Optional timeline filters change only what is displayed; printing restores all events. Downloads include the full report, a short brief, chart, typed data, calculation script and source register. See the collection methods for financial and outcome definitions.

08 / Program record

Source appendix

09 / Program record

Edition history

September 24, 2026 · Sentinel edition 1.0. First complete Sentinel report, preserving the 2020 commitment, pre-review cost comparison, 2024 reset, selected funding/contracts and reported 2026 results through the stated cutoff. Adds a short brief and reproducible chart/data. No MQ-25 or KC-46A factual re-review is implied; their September 12 cutoffs remain unchanged.