The LGM-35 Sentinel, initially known as the Ground Based Strategic Deterrent (GBSD), is a land-based intercontinental ballistic missile (ICBM) system under development for the United States Air Force. It was intended to replace all 450 Minuteman III missiles beginning in 2029, with service expected through 2075, but delays and cost overruns have pushed initial operational capability into the 2030s. The Minuteman III missiles are deployed in North Dakota, Nebraska, Colorado, Wyoming, and Montana.
In 2020, the Department of the Air Force awarded Northrop Grumman a sole-source contract to develop the Sentinel after Boeing withdrew from the bidding process. Subcontractors include Lockheed Martin, General Dynamics, Bechtel, Honeywell, Aerojet Rocketdyne, Parsons, Textron, and others.
In January 2024, the Air Force announced that program costs had increased to over $125 billion, significantly exceeding the initial $78 billion estimate, and that deployment would be delayed by two years. The cost and schedule overrun was classified as "critical", triggering a Nunn–McCurdy review. Under Nunn–McCurdy, programs in critical status are presumed terminated unless the Department of Defense certifies that they are essential to national security and no less costly alternatives exist. It was determined that the Sentinel program met these criteria, allowing it to continue, however the Air Force was directed to implement cost controls. The review, released in July 2024, also included a revised cost estimate, putting total acquisition costs at $141 billion.
The Air Force plans to procure 634 Sentinel missiles, along with 25 additional missiles for development and testing, to support the deployment of 400 operational missiles. The program also includes modernization of 450 silos and more than 600 facilities across approximately . However, it was later determined that existing Minuteman silos could not be adapted for the Sentinel, requiring new silos to be constructed at significant additional expense not accounted for in the prior acquisition costs.
Name According to the United States Air Force website, the L in LGM is the Department of Defense designation for silo-launched; G means surface attack; and "M" stands for guided missile per the 1963 United States Tri-Service rocket and guided missile designation system. The GBSD program had initially been allocated with the designation LGM-182, but for unknown reasons it was changed to the out-of-sequence designation LGM-35. The name "Sentinel" was chosen to evoke the image of "one that stands guard and keeps the watch" according to Air Force Global Strike Command's lead historian.
History In 2010, the ICBM Coalition, legislators from states that house nuclear missiles, told President Obama they would not support ratification of the New START treaty with Russia unless Obama agreed to revamp the US nuclear triad: nuclear weapons that could be launched from land, sea, and air. In a written statement, President Obama agreed to "modernize or replace" all three legs of the triad.
A request for proposal for development and maintenance of a next-generation nuclear ICBM was made by the US Air Force Nuclear Weapons Center in July 2016. The GBSD would replace the Minuteman III, which was first deployed in 1970, in the land-based portion of the US nuclear triad. The new missiles, to be phased in over a decade from the late 2020s, are estimated over a fifty-year life cycle to cost around $264 billion. Boeing and Northrop Grumman competed for the contract.
In August 2017, the Air Force awarded three-year development contracts to Boeing and Northrop Grumman for $349 million and $329 million, respectively. One of these companies was to be selected to produce a ground-based nuclear ICBM in 2020. The GBSD program was initially expected to enter service in 2029 and remain active until at least 2075.
On 25 July 2019, Boeing announced it would not place a bid for the program, citing Northrop's recent acquisition of Orbital ATK (now Northrop Grumman Innovation Systems), Boeing's supplier of solid rocket motors. Northrop signed an agreement to firewall Boeing's proprietary data after acquiring Orbital ATK. The Air Force subsequently halted funding for the Boeing project, leaving Northrop Grumman as the sole bidder for the contract by October 2019.
In December 2019, it was announced that Northrop Grumman won the competition to build the future ICBM. Northrop won by default, as their bid was the only one left to be considered for the GBSD program. The Air Force said that they would "proceed with an aggressive and effective sole-source negotiation" in reference to Northrop's bid.
On 8 September 2020, the Department of the Air Force awarded Northrop Grumman a $13.3 billion contract to develop the GBSD intercontinental ballistic missile. Work on the GBSD missiles will be done in Roy and Promontory, Utah; Huntsville and Montgomery, Alabama; Colorado Springs, Colorado; Bellevue, Nebraska; San Diego and Woodland Hills, California; Vandenberg Space Force Base, California; Chandler, Arizona; Annapolis Junction, Maryland; and other locations.
In April 2022, the GBSD's official designation was announced: The LGM-35A Sentinel. In April 2023, the USAF formally began seeking vendor information preliminary to issuing a request for proposal (RFP) for the Next-generation reentry vehicle (NGRV).
Delays and cost overruns On January 19, 2024, the USAF announced that the LGM-35A Sentinel program will exceed its original budget estimate of $95.3 billion by at least 37%, pushing the total cost to over $125 billion, and the service entry will be delayed by two years. This estimate was raised to $140.9 billion in July 2024 following a Nunn-McCurdy review. The Program Acquisition Unit Cost (PAUC) rose from an estimated $118 million per missile in 2020 to about $162 million . This increase was primarily due to rising costs in command and control systems and missile silo infrastructure.
Air Force Secretary Frank Kendall, speaking at a Washington, D.C., think tank in November 2023, said that the program had encountered "unknown unknowns" and was due for a "re-baseline." He said, "As we get more into the program, as we understand more deeply what we're actually going to have to do, we're finding some things that are going to cost money. There's no question about that."
In July 2025, The New York Times reported that an unexplained transfer of $934 million from the project had gone to retrofit a Qatari jet given to President Trump to temporarily serve as Air Force One before being given to his presidential library after he left office. The confidential nature of the total cost of upgrading the jet and fund transfer from the program sparked controversy. In the summer of 2025, Air Force Secretary Troy Meink told members of Congress that the Air Force was diverting funds from the LGM-35A Sentinel program to pay for that Air Force One work.Everstine, Brian: "U.S. Air Force Expected To Limit Changes To Qatari-Donated 747," January 22, 2026, Aerospace Daily & Defense Report, Aviation Week Intelligence Network (AWIN), retrieved January 23, 2026
In February 2026, the USAF reported that the Sentinel will not achieve initial operational capability until the early 2030s.
Warhead In March 2019, the W87 Mod 1 (W87-1) thermonuclear warhead was selected for GBSD, replacing the W78 warhead used on the Minuteman III. It was planned for GBSD to deploy in 2028, with W87-0 warheads initially being fitted to the system and W87-1 warheads being fitted from 2030 onward. This affords the Air Force a small amount of flexibility if the W87-1 is delayed.
The completion of the first plutonium pit for the W87-1 was announced in October 2024 by the National Nuclear Security Administration, after a 35-year hiatus.
The Air Force intends to deploy a single warhead on each missile. The Congressional Research Service notes that the high throw-weight of the missile could provide options for it to carry several MIRVs or penetration aids at a future time, if prospective enemies develop credible anti-ballistic missile defenses.
Testing GBSD testing is expected to take place mainly at Hill Air Force Base in Utah, and at Vandenberg Space Force Base (VSFB) in California, with missile launches from VSFB over the Pacific Ocean. Additional testing is expected to be conducted at the Army's Dugway Proving Ground in Utah and the Ronald Reagan Ballistic Missile Defense Test Site in the Marshall Islands.
On 7 July 2022, a Minotaur II+ rocket launched from Vandenberg TP-01 for a suborbital reentry vehicle (Mk21A reentry vehicle belonging to AFNWC) demonstration mission for the future LGM-35A Sentinel intercontinental ballistic missile.
Debate
Support Supporters of the GBSD include the Heritage Foundation, former secretary of defense Lloyd Austin, former secretary of defense Ash Carter, and members of Congress in the "ICBM Coalition". They argue that the ICBMs first introduced in the 1970s have had their life extended long enough and need to be replaced with a modular system in which components are easier to replace or update. In defending the importance of land-based missiles, supporters say they are the least expensive leg of the nuclear triad because they do not necessitate large maintenance crews or incur expensive refueling costs, like nuclear-powered submarines. Additionally, they argue land-based missiles are visible reminders that the US can strike back in the event of a nuclear attack, thus making them essential to nuclear deterrence.
In its annual 2021 Threat Assessment, the US Intelligence Community said China was planning to double its arsenal of nuclear weapons over the next ten years in "the most rapid expansion in its history". It also warned that Russia may expand and modernize its nuclear arsenal.
One of the main supporters of the GBSD is Senator Jon Tester (D-MT), Chair of the Senate Appropriations Subcommittee on Defense. In a March 21, 2021, interview with Defense News, Tester said, "As of right now, I think it's important that we move forward with the GBSD because I believe there's still an important deterrent." Jennifer Granholm, Secretary of Energy in the Biden administration, told the press on April 9, 2021, "We have to keep and maintain the stockpile to make sure that it is safe and effective, and we will continue to do that to ensure that we can deter nuclear aggression from other countries."
Criticism GBSD critics include former secretary of defense William Perry; the late Daniel Ellsberg, Pentagon Papers whistleblower and author of The Doomsday Machine: Confessions of a Nuclear War Planner; the Friends Committee on National Legislation (FCNL); the Union of Concerned Scientists (UCS); the Federation of American Scientists (FAS); and Peace Action. They argue that the new missiles would be not only costly, but also dangerous, increasing the risk of accidentally launching a nuclear war. Critics say that the targeting of ICBM silos, which are supposed to act like a sponge drawing nuclear weapons to deplete Russia's nuclear power, could result in the deaths of more than 10 million people. Ellsberg and author Norman Solomon argue that peace groups must oppose not only the GBSD but also the entire land-based leg of the nuclear triad to reduce the threat of an accidental nuclear war.