The Sentinel Missile Project: Risks and Costs

The new US land-based nuclear missile program, Sentinel, is experiencing major cost overruns.

This provides an opportunity to revisit the decision to deploy the Sentinel missiles to replace the existing Minuteman III land-based missiles. Congress should terminate funding for the Sentinel program. Land-based missiles are vulnerable to attack, triggering a “use them or lose them” dilemma; deploying a new generation of missiles is contrary to commitments the US made under the Nuclear Non-Proliferation Treaty, and their use would violate the international law of armed conflict; and there are better uses for the vast sums of money involved. Below is a statement by the Lawyers Committee on Nuclear Policy (LCNP) released in May 2024.

Statement by the Lawyers Committee on Nuclear Policy

Congress made a grave mistake in authorizing the unnecessary and extremely dangerous Sentinel missile, which would commit the United States to continued reliance on vulnerable silo-based intercontinental ballistic missiles (ICBMs) for almost half a century. However, massive cost overruns and delays due to skilled labor shortages and supply chain problems have provided a chance to revisit that decision. The cost of the Sentinel program now could be more than $125 billion,¹ as compared to $95.3 billion in 2020. The magnitude of the cost overruns requires under the Nunn-McCurdy Act that the program be cancelled unless it is critically needed for national defense.² It is not, and it would make the United States less secure by increasing the risk of nuclear war.

The danger of nuclear war by accident or miscalculation

The central flaw of fixed silo missiles is their vulnerability to surprise attack. As a result, any warning of possible attack triggers a “use them or lose them” dilemma. But once ICBMs are launched they cannot be recalled, even if the warning proves to have been a false alarm. The nation launching them will have condemned itself – and the rest of the world – to the horrors of a nuclear holocaust. According to reason, morality, and international law this is an intolerable situation, and the Sentinel project would perpetuate it for almost half a century.

The danger of nuclear war by mistake or miscalculation is not some remote theoretical possibility. Several times already the world has come within minutes of global nuclear war through human or machine error.³ Scientists and arms control experts have been warning for several years that developments in technology have been increasing the risks.⁴ So far, with each “close call,” the world has been lucky. But relying on a “perpetually perfect run of good luck” for our survival is “tempting fate beyond reason.”⁵

Instead of perpetuating its reliance on fixed silo missiles, the U.S. should be seeking to end it as soon as possible. If the existing Minuteman III missiles must be retained for an interim period while this is done, they should at least be taken off “launch on warning” alert. The same capacity for quick response could be retained by placing bombers on high alert, and bombers, unlike missiles, can be recalled if a false alarm is discovered. The U.S. also has a formidable force of missiles based on invulnerable submarines.

An argument sometimes advanced in favor of retaining silo-based ICBMs is that their wide distribution would act as a “sponge,” requiring an attacker to launch hundreds of missiles. However, a fatal “sponge” indeed: Recent scientific research discloses that, depending on wind conditions, dispersion of radiation from a nuclear attack on the silos would cause fatalities ranging from several hundred thousand to several million, with an average estimated death toll of 1.4 million.⁶

Moreover, the Sentinel program, like many other nuclear weapon programs, appears to ignore the scientific evidence on the climate effects of a nuclear war. At least since Robock and Toon published their landmark paper on “Self-Assured Destruction,”⁷ it has been clear that even a “successful” first strike would be suicidal for the party launching it. A rigorous study in 2022 found that a major nuclear war would cause five billion casualties because of the ensuing nuclear winter and famine.⁸

Deployment of the Sentinels would violate international law and treaty obligations, and increase the risk of proliferation

Under Article VI of the Nuclear Non-Proliferation Treaty (NPT), the U.S. and other nuclear weapon states are obligated “to pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament”. At the 2000 and 2010 NPT Review Conferences, in response to the frustration of non-nuclear weapon states at lack of progress toward these goals, the nuclear weapon states, including the U.S, committed themselves to a “diminishing role for nuclear weapons in security policies to minimize the risk that these weapons will ever be used” and to engage in processes leading to the “total elimination” of their arsenals.⁹

Perpetuating reliance on vulnerable nuclear ICBMs until late in the century would violate these commitments. It would deal a serious blow to the NPT, at a time when the treaty is already under severe pressure, and further endanger the whole non-proliferation regime. It is also true that actual use of the ICBMs, like other nuclear weapon systems, would violate the international law of armed conflict,¹⁰ and threatening their use is likewise contrary to international law.¹¹

Redundant programs of nuclear overkill drain resources from other critical defense needs

In addition to the current estimated cost of the Sentinel missile program, $125 billion, the cost of the warhead for the missile was estimated at $15 billion in 2020,¹² and tens of billions more dollars will be spent on producing the plutonium cores for the warheads.

There are better uses for these vast sums. Just in the national security sphere, funds would be better spent on, e.g., increasing the resilience of the vital U.S. satellite network, potentially threatened by a Russian nuclear space weapon.¹³ Another critically underfunded area is cyber defense. A high priority is ensuring the cyber security of nuclear command, control, and communications systems.¹⁴ It should be noted, in this connection, that the Government Accountability Office in a 2023 report indicates that Sentinel’s software system is a possible point of vulnerability.¹⁵ The head of the FBI has testified that his cyber defense personnel are severely outnumbered by hackers.¹⁶

Wasteful redundancy in nuclear overkill also exacerbates the other existential threat to human survival, by consuming assets that will be needed to avert climate catastrophe. As highlighted by a recent article in Arms Control Today,¹⁷ climate change is not only an environmental issue; it impacts and redefines national security. The already sparse funds allocated to climate change mitigation will be further diminished in the face of the increasing social, economic, humanitarian, and geopolitical costs and challenges posed by rising sea levels, mass migrations and other consequences of climate change.

Conclusion

The ICBM modernization is an act of vertical proliferation and build -up, that will further fuel a dangerous nuclear arms race. It is therefore critical for Congress to terminate funding the Sentinel program. The costs of the Sentinel program go beyond the misallocation of funds and talent—to the cost of erosion of international law. This is indeed a heavy price to pay!

Jonathan Granoff is President of the Global Security Institute, a Board Member of LCNP and a co-author of this statement.

¹ John A. Tirpak, “New ICBM Has ‘Critical’ Cost and Schedule Overruns, Needs SecDef Certification to Continue,” Air & Space Forces Magazine, January 18, 2024
² See “The Nunn-McCurdy Act: Background, Analysis, and Issues for Congress,” Congressional Research Service, 2016,
³ See William J. Perry and Tom Z. Collina, The Button: The New Nuclear Arms Race and Presidential Power from Truman to Trump, Ben Bella Books, 2020, pp. 59-65
⁴ See, e.g., “New Technologies, Complexity, Nuclear Decision Making and Arms Control: Workshop Report,” European Leadership Network, June 2021; see also Rose Gottemoeller, “The Case Against a New Arms Race: Nuclear Weapons Are Not the Future,” Foreign Affairs, August 2022
⁵ Global Zero Commission, Chair, Gen. (Ret.) James E. Cartwright, “De-Alerting and Stabilizing the World’s Nuclear Force Postures,” April 2015, p. 11
⁶ Sébastien Phillipe, “Sacrifice zones: what happens if silo based nuclear missiles are attacked?” Scientific American, December 2023
⁷ Alan Robock and Owen Toon, “Self-assured destruction: The climate impacts of nuclear war,” Bulletin of the Atomic Scientists, September 1, 2012,  
⁸ Xia, Robock et al., “Global food insecurity and famine from reduced crop, marine fishery and livestock production due to climate disruption from nuclear war soot injection,” Nature Food, 
⁹ Final Document 2000 NPT Review Conference, NPT/Conf. 2000, Vol.1, p. 15; Final Document 2010 NPT Review Conference, NPT/Conf. 2010, Vol.1, pp. 20-21
¹⁰ See, e.g., “End the War, Stop the War Crimes,” Lawyers Committee on Nuclear Policy, April 21, 2022, pp. 5-6; Charles J. Moxley, Jr., John Burroughs and Jonathan Granoff, “Nuclear Weapons and Compliance with International Humanitarian Law and the Nuclear Non-Proliferation Treaty,” 34 Fordham International Law Journal 595 (2011)
¹¹ See John Burroughs, “The Inadmissibility of Nuclear Threats,” Arms Control Today, April 2024
¹² “NNSA Estimates W87-1 Will Cost Almost $15B, GAO Questions Ready Date,” Defense Daily, September 23, 2020,
¹³ See Jon Wolfsthal, “For Heaven’s Sake: Why Would Russia Want To Nuke Space?”, Federation of American Scientists, February 21, 2024 
¹⁴ See Page O. Stoutland and Samantha Pitts-Kiefer, Nuclear Weapons in the New Cyber Age, Nuclear Threat Initiative, September 2028
¹⁵ Government Accountability Office, Weapons System Assessment, GAO-23-106059, June 2023, p. 88 (“Sentinel is a software-intensive program with a compressed schedule.”)
¹⁶ “Chinese hackers outnumber FBI cyber staff 50 to 1, bureau director says,” CNBC, April 28, 2023, 
¹⁷ Kenneth G. Brill, “A New Argument for Arms Control: Climate,” Arms Control Today, November 2023, pp. 6-11