The construction of entirely new launch silos for the U.S. Air Force’s future LGM-35A Sentinel intercontinental ballistic missile is not only reshaping America’s nuclear modernization strategy, it is also compelling a fundamental rethink of how the service protects its most sensitive assets.
Units charged with defending the nation’s land-based nuclear deterrent — primarily Air Force Security Forces assigned to missile wings — are preparing for significant updates to their tactics, techniques, and procedures (TTPs) as the Sentinel program advances. A new report from the Government Accountability Office (GAO) underscores that security policy revisions will be required early in the transition process, ensuring that defenders are trained and prepared before the first operational Sentinel missiles come online.
The GAO assessment was released just one day after the Air Force issued its own program update, reiterating that a sweeping restructuring effort is underway and expected to conclude before the end of the year. Under the revised timeline, a prototype LGM-35A is now scheduled for its first launch in 2027, with operational fielding anticipated in the early 2030s — several years later than the original 2029 initial operational capability target.
For decades, Air Force missile security has revolved around safeguarding the aging LGM-30G Minuteman III force. The United States currently maintains 400 Minuteman III missiles in hardened silos across five states — Wyoming, Montana, North Dakota, Colorado, and Nebraska — forming the land-based leg of the nuclear triad.
Security Forces Airmen routinely train to defend these remote launch facilities from ground and aerial threats, conduct convoy protection for missile transport operations, and rehearse “recapture and recovery” missions in the event a hostile force attempts to seize control of a site.
In a 2019 training scenario described by the Air Force, defenders responded to a simulated attempt to capture a nuclear asset. Security personnel inserted by Humvee and helicopter maneuvered through the launch complex, neutralized adversaries, retook the facility, and administered tactical combat casualty care. Such drills reflect the extreme seriousness with which the Air Force treats even highly unlikely contingencies.
But the Sentinel program introduces a major shift: the Air Force has decided it cannot reuse most existing Minuteman silos and supporting infrastructure. Instead, it will construct new silos, launch control facilities, utility corridors, and command centers — effectively rebuilding much of the missile enterprise from the ground up.
According to GAO, that physical transformation will require corresponding changes in security doctrine.
“DOD will need to complete Sentinel launch facility test and evaluation activities early in the transition to inform DOD and Air Force security policy updates,” the report states. “Because security forces incorporate these updates into unit-level operating instructions, these policy updates will be needed to train Air Force security forces for the transition.”
While the watchdog did not detail specific required changes, the implications are clear: new facilities with different layouts, access points, hardened structures, sensor networks, and digital architectures will necessitate new defensive playbooks.
The LGM-35A Sentinel is designed to replace the Minuteman III, which first entered service in 1970. Though the Minuteman force has undergone successive life extension programs to remain viable, Air Force leaders have long argued that the missiles are nearing the limits of sustainable modernization.
Sentinel is expected to deliver improved range, greater accuracy, enhanced reliability, and long-term sustainment benefits. It is also designed with modern digital infrastructure and open architecture systems intended to simplify upgrades over its decades-long service life.
Air Force Gen. Stephen Davis, commander of Air Force Global Strike Command, has expressed confidence in the program’s long-term adaptability.
“I think Sentinel is going to be a bit easier with some of the things we’re designing into the program — the digital infrastructure, the open architecture,” Davis said. “I think it will make it easier to upgrade and keep that missile relevant.”
However, transitioning from Minuteman to Sentinel is proving far more complicated than initially envisioned.
Originally, the Air Force planned to reuse Minuteman silos and retrofit them for the new missile. That approach was abandoned after further analysis determined that modifying 450 aging, decades-old structures would be unpredictable, costly, and potentially hazardous.
Instead, the service opted to build new silos entirely — a decision that significantly increased program costs and triggered a formal restructuring process in 2024.
The Sentinel program is now categorized by GAO as a “megaproject,” defined as an undertaking costing $1 billion or more, affecting over one million people, and spanning multiple years. Such projects, GAO notes, are “extremely risky ventures, notoriously difficult to manage, and often fail to achieve their original objectives.”
When the Air Force announced restructuring last year, projected acquisition costs had ballooned to approximately $140.9 billion — an 81 percent increase over original estimates. A revised official cost figure has yet to be released.
Air Force Gen. Dale White, serving as Direct Reporting Portfolio Manager for Critical Major Weapon Systems, has insisted that the restructuring effort is intended to reduce risk, not introduce it.
“We certainly have not lowered the bar, and we certainly have not taken on any risk by doing this,” White said in a recent interview. “The restructured program incorporates key lessons learned to ensure maximum efficiency.”
The decision to build new silos, officials argue, will ultimately reduce uncertainty and avoid the unpredictable expenses of excavating and modifying half-century-old facilities.
Nevertheless, GAO continues to warn of challenges, particularly in software development and the construction of extensive ground infrastructure — including thousands of miles of secure utility corridors linking missile sites.
Northrop Grumman, the program’s prime contractor, is scheduled to begin construction of a prototype launch silo this month at its Promontory, Utah facility. This test silo will allow engineers to refine modern construction techniques and validate design assumptions before fieldwork begins in operational missile fields.
Such a prototype may also serve as a valuable training ground for Security Forces, enabling them to rehearse defensive tactics against the specific structural realities of Sentinel facilities.
Meanwhile, construction activities are expanding across existing missile bases.
At F.E. Warren Air Force Base in Wyoming, prototyping work this summer will test innovative utility corridor construction methods intended to accelerate deployment. The first of three new Wing Command Centers is already under construction there.
At Malmstrom Air Force Base in Montana and Minot Air Force Base in North Dakota, Site Activation Task Force detachments are laying the groundwork for the Minuteman-to-Sentinel transition.
Vandenberg Space Force Base in California, though not home to operational ICBMs, is preparing critical facilities to support Sentinel’s future flight test campaign. The first Sentinel test launch in 2027 will occur from a launch pad rather than a silo, reflecting early-stage testing requirements.
Security for missile fields is a complex ecosystem extending far beyond fixed silos. It includes convoy protection for transporter-erector vehicles, security during missile loading and unloading operations, air patrols over vast rural areas, and rapid-response forces capable of reaching remote sites under adverse conditions.
The Air Force is already modernizing portions of that security architecture. The new MH-139A Grey Wolf helicopter, replacing the aging UH-1N fleet, provides enhanced speed, range, and reliability for aerial support missions over missile fields. Earlier this year, an MH-139A escorted a Minuteman III convoy for the first time.
Sentinel’s introduction will require integration of such modernized air assets into updated TTPs aligned with new facility layouts and digital systems.
Security planners must also account for worst-case contingencies. While detonating a nuclear warhead without authorization is extraordinarily unlikely due to layered safeguards, adversaries could attempt to sabotage a missile within its silo. Even a conventional explosion inside a silo would carry significant operational and environmental consequences.
Accordingly, future TTPs must address not only external assault scenarios but also potential threats targeting digital systems, access control mechanisms, and cyber vulnerabilities associated with Sentinel’s more advanced architecture.
Another complicating factor is the need to sustain the Minuteman III force longer than originally anticipated. With Sentinel now projected to achieve operational capability in the early 2030s, concerns are growing about maintaining Minuteman reliability through at least 2036.
A seamless handoff between systems is critical. Any capability gap in the land-based nuclear deterrent could undermine strategic stability and weaken the credibility of the U.S. nuclear triad.
The restructuring effort aims to minimize further schedule slips, but GAO has cautioned that acquisition strategy adjustments and potential requirement changes remain under review.
The Sentinel program represents one of the most ambitious and expensive modernization efforts in Pentagon history. Beyond the missile itself, it encompasses new silos, command centers, digital networks, utility corridors, transport systems, training programs, and security doctrines.
For Air Force Security Forces — often operating in isolated rural terrain under harsh weather conditions — the coming decade will demand adaptation to entirely new defensive environments.
New site geometries may alter fields of fire and surveillance coverage. Digital infrastructure could introduce additional cyber defense responsibilities. Updated operating instructions will ripple down to squadron-level procedures, training syllabi, and equipment requirements.
Though much attention focuses on cost overruns and schedule delays, the security dimension highlights another reality: nuclear modernization is not just about replacing hardware. It requires reengineering the ecosystem that safeguards it.
If the Sentinel restructuring proceeds as planned, and if the prototype launch in 2027 meets expectations, the early 2030s will mark the beginning of a new chapter in America’s land-based deterrent.
But between now and then, thousands of Airmen — engineers, security forces, logisticians, and missileers — will be navigating one of the most complex transitions in the history of the U.S. nuclear enterprise.
Whether Sentinel ultimately fulfills its promise of improved reliability, sustainability, and adaptability will depend not only on engineering success, but also on the ability of those entrusted with defending it to evolve alongside it.
