The program to replace America’s aging nuclear ICBM arsenal, known as the LGM-35A Sentinel, is already projected to go at least 81 percent over budget, which represents tens of billions of dollars in anticipated cost overruns. Yet, despite the program’s ballooning expenses, the Pentagon has reaffirmed its commitment to the effort, calling its continuation, “essential to national security.”

To many outside of the Defense apparatus, the Sentinel ICBM program may seem unnecessary. After all, the United States already maintains a standing arsenal of more than 400 nuclear-armed Minuteman III ICBMs, each of which can deliver its nuclear payload to targets more than 8,000 miles away, traveling at speeds over Mach 23. These weapons lay in wait, housed in hardened underground silos spanning Wyoming, Montana, and North Dakota, and represent only the land-based portion of America’s traditional nuclear triad.

A bevy of nuclear gravity bombs, spanning in yield from as low as 0.3 kilotons to as high as 1.2 megatons, serve alongside long-range air-launched nuclear cruise missiles as the airborne leg of the triad, delivered via a laundry list of bombers and fighters. And then, most importantly, a fleet of 14 Ohio-class ballistic missile submarines, each carrying 20 Trident II submarine-launched ballistic missiles (SLBMs) with multiple warheads onboard, serve as the at-sea leg of the triad while also representing the majority of America’s deployed nuclear arsenal.

The land-based Minuteman III fleet is often seen as the least important facet of America’s deterrent nuclear posture, with many experts and analysts dismissing these weapons and their hardened silos as little more than a “warhead sponge,” meant to give adversary nations such a long and daunting list of targets for any potential first strike that there will have little hope of blunting the edge of America’s nuclear response. But while this might make these ICBMs seem less important than the Navy’s deployed SLBMs, for instance, the truth is, using these isolated facilities as a “warhead sponge” might make all the difference in a nuclear conflict. 

The known and permanent locations of these ICBM silos give enemy nations a list of hundreds of targets to focus on, allowing America’s missile subs and nuclear-capable aircraft to retaliate with less interference.

In other words, with hundreds of nuclear ICBMs lying in wait beneath the grasslands of the Great Plains, adversaries planning a nuclear first strike must address the looming threat of these missiles, which are dispersed and sufficiently hardened to nearly require a direct nuclear strike on each to eliminate the possibility of Minuteman III retaliation. 

Even for Russia, which maintains the largest nuclear stockpile in the world and claims to have some 1,710 deployed warheads at any given time, this would be a serious challenge. If you assumed a broadly unlikely 100 percent hit rate, using just one Russian warhead for each of America’s known 450 Minuteman III silos, nerfing America’s ICBM fields alone would require more than a quarter of the nation’s entire deployed nuclear arsenal. If Russia opted to play it safe and devote two warheads to each silo, it would dramatically increase its chances of success, but at the expense of more than half of its deployed nuclear arms. This, of course, also means no other nation on the planet besides Russia has the warheads and the means to mount an effective attack against America’s ICBM fields. 

China’s nuclear stockpile is growing faster than any other nation’s in the world, but its entire arsenal currently amounts to just 500 or so warheads, meaning it could feasibly require every nuclear weapon in China’s inventory – not just the ones deployed – to have the same effect. 

It might be easier to think of the importance of the Minuteman III as a guard standing his post with his rifle up at the alert. Adversaries know there are other guards hidden throughout the landscape and the known location of that rifleman might make him an obvious target, but attackers still have to deal with him first if they intend to mount a successful assault. 

“The land leg’s geographic dispersal creates targeting problems for our adversaries, and our missileers sitting in an alert posture 24/7 ensures responsiveness,” explained Air Force Vice Chief of Staff General James Slife on July 8th.

It’s a cynical and deeply depressing way to see this swath of the American midwest – with these remote, but populated communities carrying that target on their backs for the sake of the rest of the nation. Yet, that’s the inherent and objectively cold-blooded math of nuclear warfare: It’s a game that ultimately, has no winners; only survivors.

And it’s in the interest of continuing this nuclear game of chicken that the Air Force is now forced to swallow the now-projected $140.9 billion cost of replacing those “warhead sponge” Minuteman IIIs, as the ballistic missiles Uncle Sam has long kept tucked beneath the northern Great Plains are rapidly aging into what the Pentagon considers to be an unsafe and strategically neutered obsolescence.

This is a problem the Pentagon saw coming. The Minuteman III program began in the early 1960s, with the first operational missiles entering service in 1970 before microwave ovens were common in American kitchens. At the time, the projected service life of these weapons was just 10 years, meaning the Minuteman III arsenal was slated to be replaced starting in 1980.

Since then, the branch has invested billions of dollars into not just maintaining these weapons but updating them to remain viable in a rapidly changing technological world. After all, these missiles and their launch facilities were designed and built before personal computers, VCRs or portable tape players had been invented. In fact, it wasn’t until 2019 that the Air Force finally migrated away from using eight-inch floppy disks (from the 1970s) to operate the Strategic Automated Command and Control System, or SACCS, that’s responsible for launch functionality.

The dated electronics found throughout the Minuteman III weapon and support infrastructure create significant concerns about cybersecurity – a defensive realm that simply didn’t exist when the weapon was being designed. Likewise, despite limited updates and upgrades over the years, the Air Force has been clear that the Minuteman III’s intercept countermeasures, or classified systems carried onboard meant to hinder an enemy’s ability to shoot the missiles down before they reach their targets, are aging out of relevance, presenting the real possibility that the longstanding nuclear deterrent philosophy of mutually assured destruction may no longer be quite so mutually assured.

More pressing than concerns about hacking, or the unrealistic idea that an adversary state could intercept hundreds of inbound warheads simultaneously, are the continuously reduced reliability of aging systems and components that are now so old that there’s no vendor, contractor, or commercial entity that can support, repair, or replace them – at least, not without a prohibitively high price tag. 

To put it into simpler terms, the Minuteman III is the nuclear equivalent of a 1969 Dodge Charger. Its iconic design and powerful legacy are still enough to leave many in awe, but nobody in their right mind would want to race in the thing today. Upgrading the Charger to make it safe and competitive on the modern race track is certainly possible with enough money and willpower, but there’s no denying that it would be a whole lot cheaper (and easier) to just buy a modern race car.

And that’s exactly what the Air Force determined in 2014 when it conducted what the Congressional Research Service describes as a “comprehensive analysis of alternatives” to the Minuteman III, ultimately assessing that replacing these aging weapons with new, more modern ones would reduce life cycle costs while also ensuring America’s ICBMs are technologically capable of outpacing emerging threats. 

Of course, there are always two sides to a debate, and others have argued that continued service life extension programs (SLEPs) on the Minuteman III arsenal, replacing aging components with more modern ones and eventually producing the ballistic missile equivalent of the Ship of Theseus, might actually be the more cost-effective solution. 

That was the position taken by a group of analysts at the Rand Corporation in 2014 who were tasked with assessing possible alternatives to a new ICBM program (then known as the  Ground Based Strategic Deterrent program). While the Air Force’s 2014 analysis concluded that modernizing the Minuteman III would cost just as much as replacing them, the Rand study presciently argued that a replacement ballistic missile system “will likely cost almost twice (and perhaps even three times) as much as incremental modernization and sustainment of the MM III system.”

Yet, even the Rand analysis left the door open for replacement to be the logical conclusion based on three potential factors. These were, firstly, if the Air Force felt the pressing strategic need to increase the capability of these weapons, which wouldn’t be cost-effective using the old missiles as a basis. Secondly, if the threat environment outside the U.S. changed in such a way that demanded it – such as emerging missile defense capabilities reducing the likelihood of success for Minuteman III strikes. Thirdly, and most pressingly, if the number of Minuteman III missiles the United States had left to launch declined.