What is the US’ Minuteman III Intercontinental Ballistic Missile?

Early Thursday, the US Air Force (USAF) was forced to blow up an unarmed Minuteman III intercontinental ballistic missile (ICBM) over the Pacific Ocean during a routine test of the weapon.

According to the US Department of Defense, the missile was fired from Vandenberg Space Force Base in California toward the Kwajalein Atoll in the South Pacific, where it operates a test site. However, the test was aborted in mid-flight “due to an anomaly,” which the Pentagon described as “any unexpected event during the test” that “may arise from many factors relating to the operational platform itself, or the test equipment.”

The US carries out such tests typically twice a year, which “helps the command evaluate the Minuteman III and gather data to keep the system effective,” the Pentagon said.

Sputnik spoke with Dr. Matthew Crosston, professor of national security and director of the Office of Academic Transformation at Bowie State University in Maryland, about the missile and its properties.

Development

“Historically, the Minuteman intercontinental ballistic missile has always been the backbone foundation of the United States military's ‘deterrence weaponry’, i.e., its land-based strategic nuclear force,” Crosston said.

Minuteman III test launch, 1994

© Wikipedia

The LGM-30 Minuteman III is the third iteration of the Minuteman series of ICBMs, the first of which entered service in 1962. The missile is named after the famed “minutemen” militias of the American War of Independence, who formed the backbone of the irregular American forces fighting the British Army.

The first Minuteman was designed to attack cities in the Soviet Union in case the US was attacked first, but after the US developed submarine-launched ballistic missiles, the Minuteman II was developed with greater accuracy and throw weight for striking hardened Soviet military targets. Later, the Minuteman III was unveiled in 1970, which could carry three nuclear warheads - a dangerous new development called a MIRV (multiple independent reentry vehicle) arrangement.

“The Minuteman III's specific capability is by definition unique, given it is the only land-based leg of the US nuclear triad,” Crosston explained.

“It was the first MIRV missile system for the US, which means it has greater versatility and capacity upon orbital reentry - i.e., a single missile is capable of targeting three separate locations. There are many other technical details that make it unique, but these specifications are really only relevant to high-level engineers and computer scientists adept with nuclear materials.”

What's the Range of Minuteman III?

While the first Minuteman missiles had a range of about 5,500 miles, putting most of the former Soviet Union in range from the northern US, the Minuteman III ICBM has a reported range of 8,700 miles, enabling it to strike almost anywhere on the planet aside from a certain area on the direct opposite side of the globe from the launch site.

How High Does Minuteman III Fly?

At its zenith, the reentry vehicle carrying the warheads is 700 miles above the Earth. That is higher than the International Space Station’s orbit of 253 miles up, for which the Minuteman III has a three-stage rocket to lift it.

How Many Minuteman III Missiles Does the US Have?

“The current arsenal consists of about 400 Minuteman III missiles that are located in hardened underground silos in the upper Midwest of America and operated ‘off-grid’ in the sense that they are not dependent on larger power systems or interdependent connected systems of communication and control,” Crosston explained.

However, at the time of its greatest extent, the US nuclear arsenal included more than 1,000 Minuteman III missiles.

In this photo taken June 25, 2014, an inert Minuteman 3 missile is seen in a training launch tube at Minot Air Force Base, N.D.

© AP Photo / Charlie Riedel

How Many Warheads Does Each Missile Carry?

When it was introduced, the Minuteman III was designed to carry three W62 Mk12 nuclear warheads, each of which had an explosive yield of 170 kilotons. This was far less than the W56 warhead placed on the Minuteman I and II missiles, which had reduced accuracy and so were given massive 1.2 megaton warheads.

Later, the W62s were replaced with larger W78 warheads, which had an explosive yield of 330-350 kilotons each - about 10 times more powerful than the bombs that destroyed Hiroshima and Nagasaki in 1945.

When the US and Russia ratified the START II treaty in 1993, the agreement banned MIRV missiles, and the US removed two of the three warheads atop the Minuteman III missiles, leaving just one each.

However, beginning in 2005, the USAF began replacing some of the W78s atop Minuteman IIIs with the W87 warheads that used to be atop the now-decommissioned LGM-118 Peacekeeper ICBMs, because the new W87s had some safety features the older W78s were not designed with. The W87 was introduced with a 300-kiloton nuclear explosive yield, but the Pentagon attempted to upgrade that to 450 kilotons at one point, and it’s unknown if they were successful.

How Old Are the Minuteman IIIs?

The first Minuteman III missiles entered service with the USAF in 1970, with construction of all Minuteman IIIs completed in 1976, making the newest Minuteman III no less than 47 years old.

Are Such Malfunctions Pushing the Pentagon to Replace the LGM-30s?

Crosston said it was “hard to ascertain” whether malfunctions such as that which caused Thursday’s test to be aborted were accelerating the Pentagon’s desire to replace the Minuteman III with a new ICBM dubbed the LGM-35 Sentinel, which it hopes to roll out by 2029.

“What is established is the fact that the Minuteman system overall has existed since the 1950s and there has long been talk within the corridors of the Pentagon about the need to at least discuss the development of new systems and/or replacements, given how much technology has advanced in the previous two decades,” he said. “Since replacement talk has existed for so long, I find it less likely that recent malfunctions or unsuccessful tests fully account for renewed interest.”

“The reality is American defense has, historically, always been passionately obsessive with the creation of new weapons systems and increased and unique capabilities. The need for American military dominance to always be maintained and preserved means, by default, that old systems get replaced by new systems.”