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While this report was in production, debate intensified over the feasibility of extending the life of Minuteman III. As a result, we concluded it would be useful to elaborate on our initial discussion of the ICBM force.

U.S. military officials, members of Congress, and other proponents argue that the service life of Minuteman III missiles cannot be extended. The USSTRATCOM commander, Admiral Charles Richard, recently said: “You cannot life-extend Minuteman III. . . . It is getting past the point of [where] it’s not cost-effective to life-extend Minuteman III. You’re quickly getting to the point [where] you can’t do it at all.”1

These assertions deserve examination. Three questions should drive the new administration’s and Congress’s analysis and decisionmaking on the ICBM issue:

  • Is it technically possible to extend the life of Minuteman III?
  • Are the costs and risks of extending Minuteman III less than those of proceeding now with GBSD?
  • Are the net benefits of pausing GBSD greater than the benefits of proceeding with it now?

We offer brief answers to these questions here, while urging Joe Biden’s administration to commission independent technical experts to study how Minuteman III life extension could be accomplished. (Such a study was proposed by members of Congress in the FY 2020 National Defense Authorization Act.2 However, Congress voted not to support it, reportedly under intense pressure from Northrop Grumman, which is slated to produce the GBSD replacement to Minuteman.)

Technical Feasibility

In 2014, the U.S. Air Force conducted an “analysis of alternatives” to examine options to life extend or replace the Minuteman III.3 The posited requirement was an ICBM inventory of at least 400 deployed missiles through 2075. (This assumption that the ICBM force would not be eliminated or reduced before 2075 is difficult to reconcile with U.S. disarmament obligations under Article VI of the Nuclear Non-Proliferation Treaty.)4

Basing analysis on a straight-line requirement projected all the way to 2075 practically predetermines the outcome. A more appropriate study would consider how long and at what cost Minuteman III could be extended under several scenarios. There is no inalterable security imperative behind the number 400 and the year 2075. Four hundred is the number the United States chose to deploy in a force structure designed to meet New START limits.5 However, the Pentagon concluded in 2013 that U.S. deterrence objectives could be met with unilateral reductions of up to one-third of the deployed arsenal—that is, reducing the deployed warhead count of approximately 1,500 warheads to 1,000. U.S. leaders could conclude now or in the next decade that a lower number would suffice—because the United States does not need this many warheads to deter Russia, or new reductions are negotiated with Russia. Or, leaders could decide, for any number of reasons, to shift some number of warheads (or all) from ICBMs to submarine-based missiles. A Biden administration review of nuclear policy should determine the number of deployed warheads the United States needs to achieve its deterrence objectives, as was done in 2013.

The independent study should also evaluate the risks that the Air Force assumes in extending Minuteman III compared with risks it posits in GBSD production. The study would also need to determine which missile components can be overhauled, which can be taken from withdrawn missiles and reused in retained ones, and which would have to be built anew. (A RAND Corporation study concluded that incremental service life extension programs were feasible, and the least costly option for maintaining an ICBM force.6) And, as suggested above, the study should assess whether and how lowering the posited required number adds to the feasibility and reduces the cost of extending Minuteman III relative to building GBSD.

Relatedly, the second line of questioning should be whether the current rate of destructive testing of ICBMs is necessary. The Air Force’s current practice of conducting (on average) 4.5 live-fire tests per year would reduce the Minuteman III stockpile below 400 deployed missiles by the year 2040.7 If fewer missiles are consumed in flight tests, the existing stockpile would last longer and more parts could be taken from some missiles to refurbish others. A reduced test rate combined with other refurbishments could enable the Air Force to maintain 400 deployed Minuteman IIIs through 2050.8 We discuss a few potential steps below.

Solid rocket motors (SRMs) are destroyed in the Air Force’s current process of testing their reliability. Yet, advances in modeling and simulation may reduce the need for destructive testing. Nondestructive testing methodologies, such as using ultrasound and computed tomography may suffice, according to SRM manufacturers and Air Force rocket propulsion experts.9 We understand that the U.S. Navy uses nondestructive testing on Trident SLBM rocket motors—it has been doing so for at least the past two decades. More generally, it determines the health and remaining life of its missiles differently than the Air Force does.10 It would be useful for the recommended commission to assess the relative merits of the two services’ approaches.

Additionally, the Air Force’s methodology for estimating Minuteman SRM operational lifetimes uses a much higher standard of reliability than is applied to aging ICBM motors used to launch payloads for the space program.11 If the Air Force thinks the Minuteman rocket motors are becoming unreliable, it should explain how many of these same vintage (and often even older) rocket motors are used to launch payloads for the space program without problem.

A separate, but relatively simple life extension issue is the aging of Minuteman solid propellant. Propellant across the missile force may begin to age and become unreliable between 2029 and 2036. The Biden administration study should assess whether a new round of solid propellant replacements, coupled with other life extension efforts, would reliably extend the Minuteman force’s life another twenty or more years.

The Congressional Budget Office and outside experts include a guidance system replacement in cost estimates for a Minuteman life extension program to maintain a reliable missile force into the 2040s. GBSD proponents assert that the new missile, with a new guidance system, will be more modular and easily upgraded than the current Minuteman guidance system, resulting in savings later in the new ICBM’s life cycle.12 The Air Force should explain what military requirements make the planned GBSD guidance system necessary. An independent commission should examine these issues, too.

As Steve Fetter and Kingston Reif argue, the Air Force has not actually determined that a Minuteman III life extension is technically infeasible. In fact, an Air Force official testified in March 2019 that “one more” Minuteman III life extension is possible before a new missile is needed.13 These technical issues deserve thorough examination by an independent commission.

Costs and Risks of Minuteman Extension versus Building GBSD

The lifetime cost of the GBSD is estimated at $264 billion.14 History suggests the actual costs would be much higher, and that it would impose difficult trade-offs. The former Air Force secretary, Heather Wilson, described the cost issues associated with nuclear modernization succinctly:

“I think the next budget [FY 2022] is the first one with a steep slope for the cost of refurbishing the nuclear deterrent. Replacing the Minuteman, replacing the Air Launched Cruise Missile, and the B-61, while upgrading the B-52, will take a lot of money. Historically, nuclear modernization has been handled in several different ways. But the Air Force can’t do this from inside a relatively static top line for the Air Force without crushing its ability to handle all of its other missions.”15

The vulnerability of silo-based ICBMs and their other deficiencies compared with submarine-deployed weapons should make the ground leg of the historically sacrosanct triad expendable. It makes little sense to invest in a new generation of over 400 ICBMs without exhausting the possibility that arms reduction agreements could be reached over the next decade or two that would obviate the perceived need for ICBMs through 2075. These are the weapons that would be most strategically desirable to reduce from the U.S. force, either unilaterally or by negotiation.

The only obvious risk of pausing on GBSD and taking steps necessary to extend Minuteman would be if the latter somehow experienced a stockpile-wide technical failure without sufficient warning to allow GBSD to be built. However, if such a failure occurred while an arms control agreement limits new ICBMs, the United States could upload a significant number of warheads to SLBMs and bombers if leaders felt it was important to do so, as both the Obama and Trump administrations acknowledged. And if there are no arms control limits on U.S. and Russian forces, U.S. leaders could readily decide to build GBSD.

Pausing GBSD Versus Proceeding With It Now

The study commission we recommend should assess the net cost differential between extending Minuteman and building GBSD not only between now and 2075, but also between now and 2040 (and perhaps another intermediate time). It is reasonable to think that pausing GBSD would save some money in the short term and defer a major long-term expenditure. Refurbishing Minuteman will not be cheap, but, again, the cost would depend on the number of weapons that are to be deployed over time.

Pausing GBSD could add to Russia’s incentives to negotiate follow-on arms reductions if New START is extended. It would be reasonable for Russians and others to assume that after the United States expends new money to build a certain number of new ICBMs, it will be less likely to negotiate their reduction or elimination than it would be now to reduce or eliminate much older systems. (A similar logic should motivate U.S. leaders to pursue a new reduction agreement with Russia before it deploys the new heavy, MIRV-capable Sarmat ICBM.)

If GBSD were being built, but still not deployed, the United States could retain some negotiating leverage, but that would make the GBSD an expensive bargaining chip, which in turn creates domestic dynamics that work against negotiating or ratifying agreements to limit such weapons. Congressional and bureaucratic stakeholders would likely pressure the Defense Department to deploy the missile across existing ICBM bases to the benefit of military and civilian constituencies in those areas and oppose efforts to “trade” the new missile away in arms control negotiations.16


In sum, ICBMs are the most problematic delivery system in the U.S. nuclear deterrent, but they have constituencies that effectively resist eliminating them. GBSD is not needed now because Minuteman can and should be extended for at least some years, and in the intervening time the desirability and feasibility of further extension versus proceeding with GBSD should be independently assessed. Extension of Minuteman III eventually requires obtaining components from withdrawn weapons, meaning that the deployed force would need to be less than 400. Warheads removed from Minuteman in order to allow refurbishment could be substituted for with SLBM uploads, if necessary. Preferably, the United States could negotiate reductions in strategic warheads with Russia such that switching from Minutemen to uploaded SLBMs would not be necessary.


1 Valerie Insinna, “US Strategic Command Chief Defends ICBM Replacement Program,” Defense News, January 6, 2021,

2 Steve Fetter and Kingston Reif, “A Cheaper Nuclear Sponge,” War on the Rocks, October 18, 2019,

3 For additional detail on the analysis of alternatives process, see this teaching note by Patrick K. Morrow of the Defense Acquisition University:

4 Dave Deptula, “Five Persistent Misconceptions About Modernizing the U.S. ICBM Force,” Forbes, December 22, 2020,

5 U.S. Department of Defense, “Fact Sheet on U.S. Nuclear Force Structure under the New START Treaty,” 2014,

6 Lauren Caston et al., The Future of the U.S. Intercontinental Ballistic Missile Force (Santa Monica, CA: RAND Corporation, 2014),

7 See Kingston Reif, “Excellent briefing by Col. Dan Voorhies on the status of GBSD,” Twitter, January 13, 2021,; and “GBSD: An Update by Dan Voorhies, 20th Nuclear Triad Symposium,” Cyber Innovation Center, December 10, 2020,

8 Todd Harrison, “Options for the Ground-Based Leg of the Nuclear Triad,” Center for Strategic and International Studies, September 2017, p. 9,

9 R. Scott Hyde, “A Solid Rocket Motor Manufacturer’s View of Sensors and Aging Surveillance,” North Atlantic Treaty Organization, September 2002,; and Shawn Phillips, “AFRL Rocket Lab: SBIR Process and Insight,” Air Force Research Laboratory, February 2019, slide 1,

10 Dave Mosher describes Trident II nondestructive tests in greater details. “In this phase of testing, the missiles are removed from the submarines and taken apart. Each component is observed closely for any signs of deterioration and tested to make sure that it functions properly. The same process is applied to missiles in the stockpile. Ground testing and surveillance can detect problems without resorting to expensive flight tests; sometimes they can detect them before those problems show up in a flight test.” It is unclear whether the Air Force performs similar nondestructive evaluations of Minuteman, and whether those evaluations can be improved to account for advances in sensor technology. “Rethinking the Trident Force,” Congressional Budget Office, July 1993,

11 Reif and Fetter, “A Cheaper Nuclear Sponge.”

12 Wilson Brissett, “Replacing Minuteman,” Air Force Magazine, December 21, 2017,

13 Per Lieutenant General Richard Clark: “We have several of the components that are becoming obsolete. The propulsion system, the guidance system, even the ability to provide the solid rocket motor fuel, we only have one more opportunity to do that for these weapons. After that, we have to—will have to buy a new weapon.” See “House Armed Services Subcommittee on Strategic Forces Hearing on Fiscal 2020 Budget Request for Defense Nuclear Activities,” U.S. Strategic Command, April 3, 2019,

14 Anthony Capaccio, “New U.S. ICBMs Could Cost Up To $264 billion Over Decades,” Bloomberg, October 3, 2020,

15 Theresa Hitchens, “2021: Air Force’s Nuke Mod Efforts Service’s Biggest Challenge,” Breaking Defense, December 28, 2020,

16 One ICBM base—Minot AFB in North Dakota—also hosts U.S. B-52H strategic bombers. The other two, F.E. Warren in Wyoming and Malmstrom in Montana, only base ICBM units. As the United States deploys a large number of B-21 bombers, it’s conceivable that the Air Force will attempt to reconstitute the air base infrastructure at any ICBM base it may close as a result of potential Minuteman force reductions. This could assuage local political concerns from each affected state’s congressional delegations.