Nuclear Attack Worst-Case Scenario Would See 90% of Americans Wiped Out

As if nuclear strikes on U.S. cities weren't potentially damaging enough, an attack on America's missile silos would kill millions due to acute radiation poisoning in a matter of days and spread radioactive fallout across the country, new modeling suggests.

A study published by Scientific American on Tuesday found that if the strategic launch bases were hit, most of the Midwest would be bathed in a more than lethal dose of radiation, with a worst-case scenario seeing most of the U.S. and Canada becoming uninhabitable.

Researchers at Princeton University's Program on Science and Global Security estimate that in the first four days after the silos were struck, between 340,000 and 4.6 million people would die—though the average death toll would be 1.4 million. They predicted that 300 million people would be at risk of a fatal dose of fallout.

The study comes after the U.S. Air Force said last year that it would be replacing its Minuteman III intercontinental ballistic missiles (ICBMs), which have been in operation since the 1970s, with the more modern Sentinel missile from 2029.

The $1.5 trillion plan will see all 400 of the older missiles replaced. Though the range and payload of the Sentinel ICBMs have not been officially released, they are thought to carry an equivalent explosive power of 800 kilotons of TNT and are expected to reach up to 6,000 miles and be capable of striking any target around the globe in 30 minutes.

Minuteman missiles have a range of 8,000 miles and carry estimated payloads equivalent to 170-335 kilotons—enough to effectively destroy the whole of Washington, D.C.

The researchers at Princeton said that while the U.S. Air Force had assessed the potential effects on humans and the environment of deploying a Sentinel, they had not mentioned what would happen if the missiles were detonated in their bases.

A Department of Defense (DOD) spokesperson told Newsweek that while it had not had the opportunity to review the report so could not directly address its findings, the Sentinel system would not increase risk to the U.S.

"The 2022 Nuclear Posture Review made clear that a nuclear war cannot be won and must never be fought," they said. "To this end, the best deterrent to adversary initiation of nuclear war against the United States or its allies or partners is a safe, secure and effective nuclear deterrent and strong and credible extended deterrence."

America's nuclear missile silo bases are located across five states—Colorado, Wyoming, Nebraska, Montana and North Dakota—and form part of its nuclear "triad," which gives the U.S. the ability to also launch nuclear strikes from submarines and aircraft if one prong is compromised.

The researchers said that to reach the nuclear missiles in the silos, which are buried underground and covered with a blast door, one or two warheads with one kiloton yields would need to land close to them.

Using archived weather data over 48-hour periods across a number of dates in 2021 to simulate the expected radioactive plume, the scientists found that the West Coast states were the lowest risk due to a prevailing easterly wind.

However, depending on the exact wind direction, the worst fallout could fall over any part of the U.S. and Canada east of Idaho. Based on weather patterns on December 2, 2021, Chicago, Illinois and D.C., among other population centers, would be in the direct path of a fatal dose of radiation.

In a worst-case scenario, almost all of Montana and North Dakota, as well as parts of Nebraska, Colorado, Wyoming, South Dakota and Kansas would receive a dose more than 10 times what is considered lethal, resulting in deaths in a matter of days. Most of the Midwest would receive a lethal dose, while elsewhere would see deaths occur in weeks.

The researchers found that most people living in North America would have a one percent chance of receiving an outdoor dose enough to cause acute radiation poisoning and deaths.

The modeling makes its predictions based on the assumption that all silo-based missiles would be struck, but the report notes that its projections have already been confirmed by a 1990 Federal Emergency Management Agency assessment which found that no part of the U.S. was beyond the risk of deadly levels of radiation.

"These maps send a clear message with which the many nuclear safety and environmental experts we spoke to concur: these are not risks that we should be taking," Laura Helmuth, Scientific American's editor-in-chief, said.

While the Pentagon stresses the need for America to have a functioning atomic arsenal to act as a deterrent against other nuclear powers, some have questioned the cost and necessity of the new missile program given the system's occasional false alarms and the advancements in U.S. submarine and aerial strike capabilities.

An accompanying opinion by Scientific American's editorial board cited former Defense Secretary William J. Perry's 2016 comment that "there is only one way to win an arms race: refuse to run," adding: "The only real way to use nuclear weapons is never. They should exist only in numbers large enough to deter their use by others, which they already abundantly do, with not one warhead more."

A DOD spokesperson said that "the attributes of each Triad leg are complementary, ensuring that the United States can withstand and respond to any strategic attack."

"After extensive review, the 2022 Nuclear Posture Review reiterated that the combination of all three legs of the U.S. nuclear Triad is the best approach to maintaining strategic stability at reasonable cost while mitigating against the risk of potential technical, programmatic or other problems or vulnerabilities," they added.

"Silo-based ICBMs have been a core element of the Triad for over 60 years, and the replacement of the Minuteman III ICBM weapon system by the Sentinel ICBM weapon system does not increase risk to the United States."