Minuteman III ICBM: Exploring the Cornerstone of America’s Nuclear Deterrence

By Girish Linganna

During a routine test of the weapon early on Thursday, the US Air Force (USAF) was obliged to detonate an unarmed Minuteman III intercontinental ballistic missile (ICBM) over the Pacific Ocean.

The missile was shot towards the Kwajalein Atoll in the South Pacific, where it maintains a test site, from Vandenberg Space Force Base in California, according to the US Department of Defence. But the test was cancelled in midair “due to an anomaly,” which the Pentagon defined as “any unexpected event during the test” that could be caused by a variety of things related to the test equipment or the operational platform itself.

According to the Pentagon, the US conducts these tests twice a year to “assist the command in evaluating the Minuteman III and gathering data to keep the system effective.”

The media outlet discussed the missile and its characteristics with Dr. Matthew Crosston, a national security expert and the director of Bowie State University’s Office of Academic Transformation in Maryland.

Crosston stated, “Throughout history, the Minuteman intercontinental ballistic missile has served as the cornerstone of the military’s land-based strategic nuclear force, or ‘deterrence weaponry'(to use as a threat ) of the United States.”

The LGM-30 Minuteman III, which debuted in 1962, represents the third generation of the Minuteman series of intercontinental ballistic missiles. The missile derives its name from the renowned “minutemen” militias, which served as the foundational element of the ad hoc American forces that confronted the British Army during the American War of Independence.

LGM is an acronym for “Land-based Intercontinental Ballistic Missile” and 30 refers to the Minuteman III model number. Therefore, LGM 30 Minuteman III refers to a land-based intercontinental ballistic missile model number 30, known as Minuteman III.

The primary purpose of the initial Minuteman was to strike Soviet Union cities as a backup plan in the event that the United States were attacked first. However, as the United States progressed in developing submarine-launched ballistic missiles, the Minuteman II was refined to be more precise and capable of penetrating reinforced Soviet military targets. 1970 saw the introduction of the Minuteman III, a perilous MIRV (multiple independent reentry vehicle) configuration capable of transporting three nuclear warheads.

Crosston explained, “The specific capability of the Minuteman III is inherently unique, as it is the sole land-based component of the United States nuclear triad.” The “nuclear triad” refers to the three components of a country’s nuclear arsenal that can deliver nuclear weapons, typically referring to land-based intercontinental ballistic missiles (ICBMs), submarine-launched ballistic missiles (SLBMs), and strategic bombers. 

Since it was the US’s first MIRV missile system, it offers more capacity and versatility during orbital reentry; for example, one missile can target three different places. Although it has many additional unique technological features, only highly skilled engineers and computer scientists who are familiar with nuclear materials should actually be concerned with these specs.

With a reported range of 8,700 miles            {14,012 Kms} , the Minuteman III ICBM can strike nearly anywhere on Earth, with the exception of a specific area on the opposite side of the planet from the launch site. In contrast, the first Minuteman missiles had a range of approximately 5,500 miles. {8,851 Kms }, which allowed them to target most of the former Soviet Union from the northern US.

The phrase “with the exception of a specific area on the opposite side of the planet from the launch site” means that the Minuteman III ICBM (Intercontinental Ballistic Missile) has a reported range of 8,700 miles and can target almost any location on Earth, except for a specific area located diametrically opposite to the launch site. This limitation might be due to factors such as the missile’s trajectory, Earth’s curvature, or other technical constraints. In essence, it implies that the missile can cover a vast range globally, but there is a small region on the opposite side of the Earth that falls outside its effective reach.

The warhead-carrying reentry vehicle reaches a maximum altitude of 700 miles {1,126.54 Kms } above Earth. That is higher than the orbit of the International Space Station, which is 253 miles

above Earth { 407.19 Kms } and is lifted by a three-stage rocket powered by the Minuteman III.

Crosston explained that the current arsenal is made up of about 400 Minuteman III missiles that are stored in hardened underground silos ( cylinderical structurs used for storing) in the upper Midwest of the United States. These missiles are operated “off-grid,” which means they are not connected to larger power systems or communication and control systems that depend on each other.

However, the US nuclear force had more than 1,000 Minuteman III missiles when it was at its heights.

The Minuteman III was intended to carry three W62 Mk12 nuclear bombs, each with a 170 kiloton explosive yield, when it was first unveiled. This was far less than the enormous 1.2 megaton W56 warhead installed on the Minuteman I and II missiles, which had decreased accuracy.

The heavier W78 warheads, which had an explosive yield of 330–350 kilotons each and were roughly ten times more potent than the bombs that destroyed Hiroshima and Nagasaki in 1945, eventually superseded the W62s. When the US and Russia approved the START II treaty in 1993, the pact barred MIRV missiles, and the US removed two of the three warheads atop the Minuteman III missiles, leaving just one each

However, the USAF started swapping out the W78 warheads atop Minuteman IIIs with the W87 warheads that were previously atop the decommissioned LGM-118 Peacekeeper ICBMs in 2005 since the latter had certain safety characteristics that the W78s did not have. The Pentagon tried, though it’s unclear if they were successful, to increase the W87’s 300-kiloton nuclear explosion output to 450 kilotons at one time.

The USAF deployed its first Minuteman III missiles in 1970, and production of all Minuteman IIIs ended in 1976, meaning that the most recent missile is no less than 47 years old.

Crosston stated that it was “hard to ascertain” if the Pentagon’s intention to replace the Minuteman III with a new ICBM called the LGM-35 Sentinel—which it aims to deploy by 2029—was being accelerated by mishaps like the one that resulted in the cancellation of  test on 2nd of November.

The overall existence of the Minuteman system dates back to the 1950s, and given how far technology has come in the past 20 years, there has long been discussion in the Pentagon corridors about the need to at least consider the development of new systems and/or replacements, he said. “I find it less likely that recent malfunctions or unsuccessful tests fully account for renewed interest, given how long replacement talk has been around.”

The truth is that American defence has always had a fierce obsession with developing new weaponry and enhancing its distinctive capabilities. New systems inevitably replace outdated ones because maintaining and preserving American military superiority is essential.

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(The author of this article is a Defence, Aerospace & Political Analyst based in Bengaluru. He is also Director of ADD Engineering Components, India, Pvt. Ltd, a subsidiary of ADD Engineering GmbH, Germany. You can reach out to him at: girishlinganna@gmail.com)