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New Air Force "Sentinel" ICBM to Fire Off 2024 - Counter Future Threats

What if the continental US were unexpectedly targeted by a massive salvo of incoming enemy nuclear missiles?

By Kris Osborn, President, Center for Military Modernization

(Washington D.C.) What if the continental US were unexpectedly targeted by a massive salvo of incoming enemy nuclear missiles, a wave large and wide enough to simply overwhelm missile defenses and explode multiple locations across the country at once? Added to this seemingly unthinkable challenge, what if the undersea and air legs of the triad were not sufficiently forward positioned or able to launch a large enough nuclear counterstrike to ensure total destruction of the attacking country?


While the nuclear-armed ballistic missile submarines such as the emerging Columbia-class and the nuclear-capable air platforms such as the B-2, B-52 and emerging B-21 are more than capable of launching a nearly immediate catastrophic response on any enemy launching nuclear attacks on the US, could they ensure the delivery of enough nuclear weapons to ensure total annihilation of the attacking country? If not, then could an adversary think it possible to prevail in a nuclear exchange by completely destroying a country while suffering smaller scale destruction itself? What then, is the deterrent against an enemy thinking it could launch a massive ICBM attack on a target country while sustaining a much smaller degree of impact itself? The answer here seems clear…. US Intercontinental Ballistic Missiles. Hundreds of ground launched ICBMs could, if launched in time, ensure the complete and total destruction of an entire attacking country with a corresponding massive “salvo” of nuclear missile attacks. Is not this assured destruction the entire premise of strategic deterrence?

If so, then there is little question that peace and safety from nuclear attack relies, at least to a substantial extent, upon the existence of a large number of ICBMs. This is why the Air Force and Pentagon are currently pursuing a nuanced, multipronged nuclear deterrence strategy which includes both sustaining a viable and functioning 1960s-era Minuteman III arsenal and sustaining steady success and progress with ongoing development of 400 new Sentinel ICBMs. The intent of this dual trajectory is to ensure there is no “missile gap,” or window of time during which the Minuteman III becomes fully obsolete and an operational Sentinel arrives. The Pentagon simply does not want to risk any kind of “gap” or deficit when it comes to a land-based nuclear deterrent, which is why weapons developers continue to fast-track the Sentinel and also fire and upgrade the Minuteman III until the end of the decade when the new ICBM arrives.

“I think we have an excellent shot at making sure that there is no gap when something unexpected occurs. The timeline for the central program is designed to make sure that there isn't a gap. We will have a 100% credible and effective nuclear deterrent continuously throughout the next several decades. If we run into challenges, and by the way, that's probably reasonable to assume there will be challenges as we get into our acquisition programs, because there always are, then we'll have to look at whether we have to adjust. Right now my expectation is that there will be no gap,” Air Force Acquisition Executive Andrew Hunter said recently at the 2022 Air Force Association Symposium.

The Sentinel maker Northrop Grumman, the industry partner supporting Hunter and the Air Force, agrees the progress on the emerging new weapon has been quite substantial.

"The team has made a lot of progress since we were awarded in September of 2020. A lot of design work is going on. We are about the enter reviews of the critical designs we have been working on over the past two year. We are building hardware we have the first couple stages of the motors cast which means the propellant has been poured into the motor. Eventually we will start firing off motors, first on the ground and then eventually get toward the first flight of the missile in 2024," Frank Demauro, Vice President of Strategic Deterrence, Northrop Grumman, told Warrior in an interview at the 2022 AFA Symposium "The test launch will be in fiscal year 2024. Ahead of that we actually fire off the different stages on the ground to make sure we are getting the performance out of them before we actually put a missile together."

As part of this highly-emphasized effort to ensure a large, functional nuclear deterrent while the Sentinel developers, the US Air Force is again test-firing Minuteman III ICBMs to demonstrate nuclear readiness after pausing a few tests in a deliberate effort to de-escalate nuclear rhetoric in response to Russia’s nuclear threats.

An unarmed Minuteman III ICBM carrying three re-entry vehicles traveled 4,200 miles during a recent test demonstration flight to verify that, despite the age of the decades-old missile, the Pentagon does maintain readiness and operate a viable ground-launched nuclear weapon.

“Air Force Global Strike Command Airmen launched an unarmed Minuteman III intercontinental ballistic missile equipped with three test re-entry vehicles from Vandenberg Space Force Base, California, on Sept. 7 at 1:13 a.m.,” an Air Force statement says.

The idea of continued Minuteman III ICBM test launches is to verify that the decades-old upgraded ICBM can still function as a nuclear deterrent and hold adversaries at risk. However, despite literally decades of upgrades, an interesting new study from the RAND Corporation finds that the 1960s & 1970s-era ICBM simply cannot effectively counter new missile defense technologies being developed by great-power adversaries.

The Sentinel ICBMs will replace the 400 Minuteman III ICBMs currently in service for more than 50 years in Air Force missile fields at F.E. Warren Air Force Base (AFB), Wyoming; Malmstrom AFB, Montana; and Minot AFB, North Dakota, a report from the Air Force Nuclear Weapons Center says.

Although U.S. defense officials emphasize that the Minuteman III is able to fulfill its mission, the system is anticipated to have “increasing difficulty penetrating future adversary defenses,”according to the 2018 NPR (Nuclear Posture Review), the RAND report, “Modernizing the U.S. Nuclear Triad: The Rationale for a New Intercontinental Ballistic Missile | RAND” says.

It would make sense that additional targeting technology would be needed in light of a number of advancements made by potential adversaries. China, for instance, is known to operate road-mobile ICBM launchers with multiple re-entry vehicles able to pinpoint multiple targets from a single missile, something which enables rapid targeting transitions and repositioning prior to launch if needed.

“Senior military officials have made clear that a comprehensive overhaul of the U.S. ICBM force is needed to increase targeting flexibility; to mitigate improvements in adversary missile defenses; and to strengthen defenses against cyberattacks that could undermine the system’s responsiveness and degrade communication in a crisis,” the Rand study says.

China is now also building ground-based ICBM silos to fortify its nuclear arsenal with fixed launch sites. Such a massive increase in nuclear weapons would seem to require a need for larger numbers of nuclear weapons to respond in the event of a massive, “bolt-out-of-the-blue” attack.

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“The number and types of targets that U.S. nuclear forces might need to hold at risk to deter an adversary's use of nuclear weapons in a crisis or conflict are changing—and can be expected to continue to change in complex and unpredictable ways over the next several decades,” the report says.

Another reason newer targeting technology is needed, the study specifies, is because adversaries are increasingly developing advanced missile defenses and countermeasures designed to intercept, stop or defend against incoming ICBMs. Therefore, in order to establish a credible deterrent and succeed in holding China at risk, advanced guidance technology, flight trajectory enhancements and paradigm-changing targeting ability.

“That thing is so old that in some cases the drawings don’t exist anymore,” Adm. Charles Richard, Commander of US Strategic Command, told a January 2021 virtual conference audience according to the RAND report, stating unequivocally: “You cannot life extend the Minuteman [III].”

While the RAND report says the exact nature of the technological enhancements to the GBSD have not been described publicly, the Rand study details a number of key performance parameters and enabling technologies that are informing and being integrated into the GBSD.

“The GBSD program includes new missile and guidance systems, launch facilities, command centers, and test and integration facilities, as well as modifications to ensure alignment with enterprise wide improvements of NC3 systems (command and control),” the study states.

Through a digital engineering process wherein computer simulations are able to replicate key weapons performance parameters and make technological assessments, the GBSD is being engineered to bring new levels of reliability, targeting and guidance technologies to sustain the U.S. ground-fired ICBM fleet well into the 2070s and beyond. Software upgrades, for instance, can add new guidance systems, reliability technologies and targeting sensors to the weapon as new innovations emerge, an important factor given that the new ICBM slated to serve for decades and operate against a new generation of enemy threats and countermeasures.

“The GBSD program has a phenomenal foundation for success because it established a pioneering use of digital engineering….and the very close cooperation between the government team and industry at the time to make good choices, good design choices and trade offs, to make sure that we're able to meet the operational requirements. So I think we're in really good shape. Having said that, acquisition is always hard, there will be challenges, and we're in a good position to be able to overcome those when they arise,” Hunter said at AFA.

Northrop weapons developers align with Hunter, telling Warrior that digital engineering allowed engineers to "make adjustments as they go" throughout the developmental process and ensure rapid progress. Senior Air Force leaders have in recent years explained that the digital engineering process enabled weapons developers to analyze and compare key performance parameters of as many as eight or nine different designs without having to bend metal or build different prototypes.

Interestingly, breakthroughs with digital engineering have enabled computer simulations to closely and very accurately replicate key weapons performance parameters.

"The digital component of this was very key. Before the EMD contract was awarded to us, we began designing this in a digital way with model-based systems engineering so we would get through the design iterations much faster than if you did it in a standard way. Different types of design analysis cycles, design cycles of the ground system could all be done digitally, so you could check it out digitally, adjust it digitally before we start building hardware," Demauro said.

The possibility for ongoing modernization was intentionally built into early designs of the Sentinel weapon, due to the use of digital engineering techniques able to replicate technological detail and help establish common computer standards enabling continued upgrades. It would make sense that the weapons were built with a specific mind to ongoing modernization, given that the U.S. Air Force has a long history of upgrading and maintaining ICBMs.

Air Force 3-star Lt. Gen. Jack Weinstein, Deputy Chief of Staff for Strategic Deterrence and Nuclear Integration, did tell Warrior in an interview years ago that the emerging GBSD was being engineered for increased reliability, flight trajectory and targeting.

During his discussion with Warrior years ago, Weinstein explained the rationale behind the Pentagon’s concept of deterrence and the need to maintain a strong, ready nuclear arsenal. Weinstein cited the work of a famous 1940s World War II-era philosopher named Bernard Brodie. Brodie, a Yale Professor in 1945, envisioned what is now understood as a famous paradox central to nuclear deterrence. Throughout human history, weapons have always been created to “use” against or “kill” an enemy. The served a specific purpose and had a specific function. The “intent” has always been to “use” them in conflict. Nuclear weapons, however, are entirely different as, arguably for the first time in human history, they are weapons intended “not” to be used by rather “stop,” “prevent,” or “avoid” military confrontation. Essentially, nuclear weapons are built with the intent and hope that they will “never be used.”

Brodies 1946 Essay, called “Implications for Military Policy,” and Essay in The Absolute Weapon: Atomic Power and the World Order published by Yale Universities’ Institute of International Studies, emerged just following the nuclear attacks upon Hiroshima ending WWII. His basic premise is clear – the promise of total, catastrophic destruction – prevents war.

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“If the atomic bomb can be used without fear of substantial retaliation in kind, it will clearly encourage aggression. So much the more reason, therefore, to take all possible steps to assure that multilateral possession of the bomb, should that prove inevitable, be attended by arrangements to make as nearly certain as possible that the aggressor who uses the bomb will have it used against him. If such arrangements are made, the bomb cannot but prove in the net a powerful inhibition to aggression,” Brodie writes in the Yale essay, published by Air Force Magazine.

While senior military leaders and members of Congress cite a long-list of reasons why the Pentagon needs to stay on course to deliver the new Sentinel ICBM by 2029, there is a particular high-tech concern being echoed by weapons developers related to continued use of the upgraded Minuteman III ICBM. Simply, it could be hacked.

While the RAND report was careful not to elaborate on specifics related to technical threats, the essay did make the general point that the upgraded Minuteman III ICBM is simply insufficient to address a new threat environment. For instance, Russian and Chinese “cyber-hacking” technology and fast-evolving development of space weapons and jamming technologies have massively increased the threat equation when it comes to ensuring that a Minuteman III will be able to stay on course to a target.

The RAND study takes up this question and cites comments from Adm. Charles Richard, Command of US Strategic Command, specifically highlighting potential adversaries “cyber capabilities.”

The text of the report quotes Richard saying “I need a weapon that can fly and make it to the target. Minuteman III is increasingly challenged in its ability to do that…… “[t]here is almost no possibility of an upgrade (to the Minuteman III) on that relative to the threat.”

By contrast, the new Ground Based Strategic Deterrent (called the Sentinel) is being engineered with what the RAND study calls a “dedicated cybersecurity component tasked with integrating cyber requirements throughout the system design.” The RAND essay goes on to say that this current cyber focus related to The Sentinel is a “stark contrast to the Minuteman III, which was first developed and fielded before the invention of the internet and which senior defense officials have cautioned can no longer be retrofitted to meet evolving cyber threats.”

While many of the specifics related to these threats are not likely to be available for security reasons, there do seem to be a few areas where enemy cyber attacks might focus. Certainly computerized ground-based command and control networks could be targeted with intrusions, denial of service or malware attacks. Guidance systems could be targeted by software programmable RF or EW signals seeking to “jam” an ICBMs flight trajectory toward a target and communications networks engineered to relay time-sensitive threat information to decision-makers could also be targeted. For several years now, the Air Force has been working on implementing a 7-point cyber security effort intended to increase cyber resilience by finding and addressing potential vulnerabilities early in the developmental process.

The intent, first outlined by Air Force Materiel Command years ago, is to “bake in” cyber protections by identifying possible risks during the prototyping and early digital engineering phases of development. Digital engineering is one reason the new Sentinel is on track to emerge by 2029, because weapons developers had opportunities to examine multiple design models before actually “bending metal.” Addressing cyber security was likely a major part of this, given the fast-changing threat equation.

As part of the Sentinel preparation and technological maturation process, the Air Force has been working with Northrop Grumman to engineer an entirely new command and control system, computing infrastructure and networking ability. Some of the specific efforts have involved finding ways to ensure that “enemy intrusions” cannot access any kind of launch protocol system.

The advanced Command and Control is also likely to secure data transfer from threat detection systems to higher authorities to shorten the timeline or notification curve between when senior decision makers learn of a threat and responsive weapons systems are put on alert. This incorporates space connectivity with secured and fortified ground control stations in position to quickly integrate with ICBMs should there be some kind of unanticipated “bolt out of the blue” attack.

The growing extent to which weapons systems are cyber reliant reinforces the need to harden command and control networks and computer processing for the new ICBMs, as advanced connectivity can bring unprecedented advantages while also introducing some risks. This may be why the entire hardware and software infrastructure necessary to support the new ICBMs is essentially being rebuilt with upgradeable, securely developed technologies.

Finally, along with designing and building the missiles themselves, prototypes of which already exist, the Northrop Grumman-Air Force effort includes a rebuilding of the entire ICBM infrastructure to include new launch facilities and launch centers, as well as new software and Command and Control technology. Northrop Grumman is reconstructing as many as 450 launch facilities and building the first prototype components of the ICBM, which will first fire off in the next several years.

Nuclear Dyad or Triad

Could the US effectively achieve strategic nuclear deterrence with a “dyad” rather than a “triad,” a concept now being introduced by some members of Congress and advocates of varying degrees of nuclear disarmament or a simple reduction in the size and scope of the US nuclear arsenal?

The idea, while facing significant bi-partisan opposition in Congress and concern from Pentagon weapons developers, involves a suggestion to essentially “save money” by canceling the new US ICBM slated to emerge at the end of this decade. The thinking is that the Pentagon does not need to build 400 new ICBM land-fired nuclear weapons because the two other “legs” of the triad, air-and-sea, would be sufficient for needed strategic deterrence.

A recent RAND study takes up this specific issue in depth and specifies reasons cited by those suggesting a cancellation of the Sentinel, a new ICBM slated to enter service by 2029.

“In the judgment of senior defense officials and military officers, replacing the Minuteman III with GBSD is essential to maintaining a viable land-based strategic deterrent,” the RAND report states… Modernizing the U.S. Nuclear Triad: The Rationale for a New Intercontinental Ballistic Missile | RAND.

Proponents of moving to a “dyad” point to added cost savings and risks of a possible miscalculation or accidental launch. Others favoring cancellation of the Sentinel cite the possibility of continued modernization of the 1960s-era Minuteman III, something which is widely dismissed as possible by Pentagon and Congressional decision makers.

While the report details numerous perspectives on the issue, the text of the RAND study takes the clear position that the US is in dire need of a new ICBM given the fast-changing threat environment.

Should the land-leg of the “triad” be dissolved, the US would be left to relying only upon the sea and air leg of the triad, meaning submarine-launched nuclear-armed missiles and air-dropped nuclear weapons carried by a B-2, B-21 or F-35A would have to suffice as a way to deter a potential enemy from launching a nuclear attack. “No Way,” according to the Pentagon and many members of Congress, who say such a move would leave the US extremely vulnerable to a massive “bolt-out-of-the-blue” enemy nuclear attack. The concept here would be for an enemy to launch a large-scale salvo of nuclear weapons at one time to overwhelm defenses and destroy or cripple critical elements of the US infrastructure to achieve victory on a large scale before a counterattack could be launched.

The only way to stop this, proponents of the Sentinel and GBSD maintain, would be to ensure a massive “salvo” kind of nuclear response. The idea is to prevent an adversary from thinking there might be any way to “win” a nuclear war. After all, the premise of strategic deterrence rests upon a particular paradox, wherein devastating weapons are developed and fielded for the specific purpose .. of keeping the peace. Arms to prevent nuclear war, is the thinking behind the Pentagon’s deterrence posture, and many senior leaders point out it is something which has proven effective to a large extent because there has not been great power war since WWII.

The RAND corporation study also details many reasons why the Pentagon's aging, 1960s-era Minuteman III simply cannot be upgraded or sustained in any viable way as the US pivots to respond to a fast-changing global nuclear threat environment.

Given this, the RAND study says that the Pentagon needs to remain on course to field the new Sentinel ICBM by 2029, something now being questioned by some critics from lawmakers and various nuclear disarmament groups.

“By 2030, it will have been 20 years or longer since the solid-rocket motors, guidance sets, and propulsion rocket system engines in the fleet were replaced or refurbished. Those subsystems continue to age, as do other components that have never been updated,” the RAND report states.

Drawing upon extensive research, the RAND report takes a clear position, stating “The first and perhaps most compelling argument advanced for fielding a new ICBM is that it is no longer technically feasible nor cost-effective to continue extending the service life of the Minuteman III.”

The text of the study includes a lot of detail related to practical and technical reasons why the Minuteman III can no longer be upgraded due to a variety of factors such as “corrosion, water intrusion, collapsed conduits, misaligned doors, and bulging walls are prevalent.”

The RAND essay quotes Maj Gen Anthony W. Genatempo, director of the Air Force Nuclear Weapons Center, expressing concern that the Minuteman III’s 60-year-old heating, ventilation, and air conditioning systems could fail, an event that “would take a missile off line for an unknown amount of time as it is fixed.”

Also, Air Force analysts made an interesting and potentially surprising finding several years ago, calculating that developing the GBSD Sentinel would actually be much less expensive than further upgrading the Minuteman III by as much as $38billion.

There is also a maintenance issue with the Minuteman III, according to the report, which says that the infrastructure and facilities themselves built to support the ICBMs were constructed in the 1960s, and exhibiting “serious aging issues.”

“Additionally, much of the specialized and unique gear required to maintain the missiles on alert (e.g., vehicles, handling equipment, diagnostic test sets, and cables) is simply worn out,” the report says.

Overall, the report takes the position that Cold-War era ICBMs from “half century ago” were initially build to operate for a ten-year service life.

“Despite continued support for the Triad, programs to replace the Minuteman III were deliberately and repeatedly deferred in favor of extending the aging missile’s service life until the Obama administration decided to develop and deploy a new ICBM after extensive study of alternatives.

Osborn previously served at the Pentagon as a Highly Qualified Expert with the Office of the Assistant Secretary of the Army—Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He has appeared as a guest military expert on Fox News, MSNBC, The Military Channel, and The History Channel. He also has a Master’s Degree in Comparative Literature from Columbia University.