How Many Sentinel Missiles Does the United States Need?

Minuteman III Test Launch

The U.S. Air Force deployed its first Minuteman missile in 1962. There’s no getting around this basic point, that America’s intercontinental ballistic missile fleet is a Cold War relic. At the height of the Cold War, there were more than 1,000 silos dotting the western United States. The latest iteration, the Minuteman III, was first deployed in 1970. Over the last 40 years, the Air Force has spent billions on replacing guidance systems, rocket motors, and power systems, in addition to patching up aging launch facilities and maintaining an outdated command and control system. Critics decry the land-based leg of the nuclear triad as having a “hair trigger” that threatens the world and would like to see the entire system disestablished. And recent events give this argument some justification.

The Air Force intends to replace the Minuteman III with the LGM-35 Sentinel missile. The Sentinel missile is getting increased scrutiny lately due to critical cost and schedule slips. Originally estimated in 2020 to cost $95.3 billion over its 10-year development, it now may cost upwards of $125 billion and slip past its expected initial deployment date of 2030. As a result, the average procurement cost per missile will rise to $162 million from an initial $118 million. This triggered a legal process known as the “Nunn-McCurdy breach” in which the Air Force must now justify the continuance of its program and develop a new cost and schedule estimate that is acceptable to Congress.



While this review will not necessarily result in the elimination of the program, one might question why the Air Force requires 400 missiles armed with nuclear warheads today. While the Cold War is over, the continued presence of nuclear threats to the United States demands a response. The combination of bilateral arms control agreements, deterrence theory, and presidential direction, along with bipartisan congressional approval, has resulted in the decision to retain 400 land-based missile silos for the purpose of strategic stability between nuclear-weapon states.

The U.S. Nuclear Posture Has Changed

There is a lot of baggage associated with the U.S. nuclear stockpile other than the fact that its delivery systems and warheads date back to the Cold War, when there were understandable concerns about a global nuclear exchange between the Soviet Union and United States. There have been five Nuclear Posture Reviews since 1990, and every administration — three Democratic, two Republican — has reaffirmed their view that the United States needs a “strategic triad” of land-based ballistic missiles, strategic bombers armed with gravity bombs or cruise missiles, and ballistic missile submarines. Part of this rationale has been the desire to counter Russia’s and China’s continued modernization and growth of their strategic nuclear weapons and delivery systems. The debate over the continued need for land-based ballistic missiles focuses on whether these two states in particular are in fact deterred from using nuclear weapons against the United States because of these missiles and, if so, whether continuing to upgrade Minuteman III missiles would be a more prudent approach to maintaining that deterrent.

It’s difficult to dispassionately talk about the need for nuclear weapons in the context of 21st-century conflict. Nuclear weapons are simultaneously seen as political tools of national strategy, as tools of deterrence against aggressive neighbors, and as military warfighting tools. Scholars and military analysts have debated deterrence theory for literally decades without agreeing as to what extent other nations’ political leaders can be deterred or compelled to act because of threats of nuclear weapons use. It is true both that there have been no catastrophic uses of nuclear weapons since 1945 and that reducing the world’s number of nuclear weapons is seen as increasingly important. As Colin Gray remarked in his book Modern Strategy, “Categorization of nuclear weapons … as thoroughly as ‘Bad Things’ … provides some emotional and intellectual satisfaction, but inhibits understanding.”

Because a great deal of nuclear-related issues (weapon locations, warhead yields, accuracy, targeting plans) are classified, it further inhibits the public’s ability to understand why particular nuclear weapons are needed as opposed to other options. Instead, the U.S. military relies on rote phrases such as “ICBMs are the most responsive leg of the Triad” as opposed to the submarines being the most survivable leg and strategic bombers being the most flexible leg. The process by which land-based missile crews would receive orders and launch the missiles relies on an extensive and complex architecture of command, control, and communications that is secure, redundant, and survivable. Missiles will only be launched if the president authorizes the action, and never launched if that person does not. While this requires the highest level of standards and diligence, the Air Force’s nuclear enterprise has on occasion been rocked by scandalsthat cause some to question its relevance today.

The requirements for a land-based leg of the triad remain largely the same as 60 years ago — to complicate the decision by a Soviet (now Russian) government to use nuclear weapons against the homeland by making it too difficult for a nuclear first strike to succeed. While the Cold War ended in 1990, nuclear weapons still exist in China and Russia for the same reason that the United States has them. Because nuclear-tipped missiles can destroy a city in 30 minutes after launch, they present the highest existential threat to a major power. The rationale for retaining land-based missiles is largely that other nuclear weapon states have not given up theirs, and verification of a complete ban on nuclear weaponswould be politically challenging. While nuclear deterrence theory and rationales for the triad can be mysterious, we can try to understand how the Air Force has developed the numbers for the Sentinel program.

Arms Control Constraints

While people like to refer to land-based missiles as Cold War relics, the decision process for developing and employing nuclear weapons was very different back then. The Air Force’s Strategic Air Command enjoyed a period of significant growth between 1945 and 1960, while the U.S. nuclear weapons stockpile increased from three to over 25,000 in that same period. The Air Force leadership had a certain amount of freedom to identify what it thought was required to counter the threat of Russian nuclear weapons. Fred Kaplan notes in his book The Bomb that the Air Force wanted 2,300 Minuteman missiles in 1961, but Defense Secretary Robert McNamara would only go for 1,000. Of those, over half had multiple warheads, resulting in a total of 2,100 deployed nuclear warheads on land-based missiles.

As the Soviet nuclear arsenal quickly grew larger than U.S. numbers, American political leaders recognized the need to stop this escalation. Arms control agreements were directly aimed at reducing how many missiles were deployed and what they carried. The first Strategic Arms Limitation Talks (SALT), signed in 1972, restricted the number of land-based missile silos and ballistic missile submarines to existing levels. For the United States, this meant 1,054 land-based and 656 submarine-launched missiles. SALT II capped all strategic forces to a total of 2,250 nuclear delivery launchers, of which only 1,320 could have multiple warheads, but it was not ratified by the U.S. Senate due to the Soviet invasion of Afghanistan in 1980.

The first Strategic Arms Reduction Treaty (START) was signed in 1991 and called for a reduction on overall nuclear warheads to 5,000, with half of those to be deployed on ballistic missiles. Both the United States and Russia would be limited to 850 land-based missiles, while also reducing the numbers of operational strategic bombers and submarines. This caused the closure of Minuteman missile fields at Ellsworth Air Force Base, Whitman Air Force Base, and Grand Forks Air Force Base, as well as the Peacekeeper missile field at F.E. Warren Air Force Base. The New START treaty, signed in 2010, further reduced the total nuclear warheads to 1,550. This resulted in the Air Force removing 50 Minutemen IIIs out of silos at F.E. Warren, leaving a total number of 400 deployed missiles. The Air Force is keeping the 50 empty silos “warm” so as to have the option to refill them if national guidance changes.

Defense Acquisition Is Largely Unchanged

The Defense Department treats the research and development of nuclear weapon systems largely the same way as it does any other weapon system, using the same acquisition guidelines and cost controls, but there are a few significant differences. First, the president sets the guidance for how nuclear forces are to be employed. The Air Force and Navy can only recommend how they would like to organize, train, and equip their nuclear forces. In addition, the Defense Department has to rely on the Energy Department to design and produce the warheads that are mounted on military delivery systems, and a high-level Nuclear Weapons Council meets to review military requirements and oversee the modernization program. But every year, the Air Force’s nuclear community has to fight for and justify its requirements against the service’s many other conventional programs that are being developed.

Past Air Force leaders complained about a 20-year “procurement holiday” in which the Defense Department deferred its nuclear modernization and the Air Force budget prioritized fighters, bombers, and tankers. This in part led to significant delays in replacing the Minuteman III, in addition to modernizing the B-52 engines and replacing the helicopters that monitor the missile fields. Congress funded the current nuclear modernization program that President Barack Obama proposed in 2010. This advanced the Air Force’s nuclear modernization portfolio to being something more than just one of the many Air Force acquisition priorities. Air Force Global Strike Command stood up an Intercontinental Ballistic Missile Modernization Directorate to develop its military requirements for the Sentinel. All of the Air Force’s nuclear programs are centrally managed by the Air Force Nuclear Weapons Center and the Program Executive Office for Strategic Systems, with a Program Executive Office for Intercontinental Missiles being stood up.

The Air Force’s planned acquisition is 659 Sentinel missiles, to include 400 for the silos at Minot, Malmstrom, and F.E. Warren, and the remainder for replacements and test flights (three per year) to last through 2075. The acquisition program also will replace, not modernize, the launch control centers, many of which may be leaking toxic chemicals, and hardening the intricate web of communication systems against cyber intrusions that could reduce their reliability. The number of missiles could be higher or it could be lower, but at this point in time it will not be zero. The Air Force will execute whatever the president and Congress wants the number to be.

The Air Force Global Strike Command’s modernization chief noted, “Not to be flippant, but show me a program that doesn’t have higher costs at the end than what were initially projected.” One can argue as to whether military acquisition offices are lowballing their initial program cost estimates or just optimistically presenting a best-case scenario, but there is nothing particularly unusual about how this acquisition program is being conducted. The prime objective is to meet the 2030 deadline to deploy the first batch of Sentinel missiles, and that might mean spending more money to overcome unexpected challenges that arise between now and then. The congressional delegations with missile bases in their districts will heartily welcome the execution of defense funds to modernize this capability.

Is There a Right Number?

There is no “right answer” for the number of required land-based silos to meet U.S. national security goals. As these weapons are political tools of power, it is up to the president, with advice from staff, to determine the desired nuclear employment strategy. There have been numerous studies on a “dyad” nuclear posture, and usually the land-based missile is the system that is proposed to be eliminated. Usually the rationale is either “it will save on costs and we still have bombers” or “we can’t afford an error that will end up launching all our missiles.” Neither argument has been particularly persuasive. As many calls as there have been to eliminate land-based missiles, there have been equal numbers of calls to retain them as a distinct capability that enhances global stability.

Congress usually eschews eliminating defense systems, no matter how old or vulnerable they might be in a modern context. Could the United States manage with fewer land-based missiles than today’s numbers? It depends on the context. Certainly the number has gone down from 1,054 silos in the 1960s to 400 silos today, and there is always the possibility that a new technology — hypersonic cruise missiles or road-mobile missiles or fractional orbital bombardment systems — could be adopted in their place. Some will still advocate for not proceeding with the Sentinel and continuing to pursue life extension programs for the Minuteman III, even as authorized funds pour into the Air Force’s coffers to develop the new missile. However, the 2022 Nuclear Posture Review suggests that any alternative to the Sentinel that extends the Minuteman III — which was never intended to last past 10 years, let alone 50 — “would increase risk and cost.”

There are calls to increase the importance of land-based missiles, notably in the 2023 report from the Congressional Commission on the Strategic Posture of the United States. While the report does not call for additional missiles, it does suggest that the United States consider putting multiple warheads on the Sentinel and fielding missiles in “a road mobile configuration.” There are no specific numbers in its recommendations. Much of the commission’s concern arose from a worst-case scenario of China and Russia simultaneously attacking the United States, and that a future U.S. nuclear stockpile needs to keep pace with the growing number of Chinese and Russian intercontinental ballistic missiles. This is a ridiculous argument for multiple reasons. First of all, strategic deterrence does not rely on a math equation. Second, it’s not as if U.S. land-based missiles have to take out all of the Chinese and Russian silos on their own. How land-based missiles factor into nuclear employment plans is too complex and dependent on multiple factors to outline here.


The Air Force is going to spend more than $48 billion to modernize 76 B-52 bombers so that they can continue to fly combat missions for another 35 years. This is just to point out that the argument over the Sentinel program — like many of the Defense Department’s major defense acquisition projects — is not just about the money. Nuclear modernization enjoys bipartisan support and is not going away. If the Sentinel program was cancelled, the money would move to maintaining the Minuteman missiles and putting strategic bombers on alert. Few, if any, in Congress will view a Nunn-McCurdy breach as the signal to kill the Sentinel program, especially as it will be fielded in less than 10 years’ time. No one likes the idea of nuclear warfare, but at the same time, the argument against modernizing the U.S. nuclear stockpile is dangerously naïve. The Sentinel will eventually be fielded and the United States will maintain a degree of strategic stability against China’s and Russia’s nuclear arsenals.

It is, however, important to have this discussion about “how many nukes are enough” with the American public, in as much as they need to understand the need for this mission. The Cold War ended decades ago. We do not have civil defense shelters anymore and we worry about natural disasters more than a nuclear attack when the emergency broadcast signal goes off. But because nuclear weapons still exist, we need to discuss and develop concepts that reduce the possibility that they are used. That will include a certain number of land-based missiles within a strategic triad. Academics and political analysts are always debating as to what America’s nuclear posture ought to be, but it comes back to the military acquisition professionals who take direction from the White House and turn that into a capability that can be trusted to meet the most important mission of the Defense Department.



Al Mauroni is the director of the U.S. Air Force Center for Strategic Deterrence Studies and author of the book BIOCRISIS: Defining Biological Threats in US Policy. The views expressed in this article are those of the author and do not necessarily reflect the official policy or position of the Air Force, the Department of Defense, or the U.S. government.

Image: U.S. Air Force Photo by Staff Sgt. J.T. Armstrong