“Low-Yield” Nuclear Weapons Could Pose Greater Threat of Nuclear War

Each year on March 1, Marshallese around the world mark Nuclear Victims Remembrance Day to commemorate all who have suffered and seek justice following 67 U.S. nuclear weapons tests at Bikini and Enewetak Atolls in the Marshall Islands (1946-58).

On that day in 1954, the U.S. conducted its largest ever nuclear detonation, the Castle Bravo test, a 15-megaton thermonuclear bomb 1,000 times more powerful than the bomb dropped on Hiroshima. The Bravo shot caused widespread suffering in the Marshall Islands and spread radioactive fallout around the world.

Sixty-eight years later, the United States and eight other nations continue to spend extraordinary sums — over $72 billion total in 2020 — on maintaining, expanding and modernizing their nuclear arsenals. While the overall number of nuclear weapons has been reduced dramatically from a Cold War peak of more than 70,000, today the U.S. and Russia possess 90 percent of the approximately 12,700 remaining nuclear weapons.

With the Russian invasion of Ukraine and NATO forces deployed to the alliance’s eastern flank, concerns over nuclear risks rise to the fore. Matt Korda, senior research associate with the Federation of American Scientists’ Nuclear Information Project says that at the present moment, the conflict remains well below the nuclear threshold. “While many systems deployed to Ukraine are dual-capable — meaning that they can launch both conventional and nuclear weapons — there is no indication that nuclear weapons or nuclear custodial units have been deployed along with them,” Korda says.

He cautions that, as in any war, the risks of miscommunication and irrationality remain high, and told Truthout, “it’s incumbent on all sides to ensure that there is no danger of nuclear escalation.”

Even as U.S. presidents pay lip service to “a world without nuclear weapons,” the U.S. currently has an estimated total inventory of just over 5,400 nuclear weapons ranging from 0.3 kilotons up to 1.2 megatons. A warhead with a yield (amount of energy released by a nuclear explosion) of one kiloton is equivalent to 1,000 tons of TNT. One megaton equals 1 million tons of TNT.

A nuclear weapon’s yield dictates what type of target a particular weapon can threaten. The highest yield warhead in the U.S. arsenal is the B83-1, a 1.2-megaton strategic gravity bomb (80 times more destructive than the bomb that destroyed Hiroshima). By contrast, the lowest-yield warhead in the U.S. stockpile is the B61-3, a 0.3-kiloton bomb with an adjustable yield that can be “dialed-up” to 170 kilotons.

Other U.S. nuclear warheads range from 5 to 455 kilotons. By comparison, the bombs that destroyed Hiroshima and Nagasaki were approximately 15 and 21 kilotons respectively.

Although warheads today have a lower yield than those tested decades ago, most are far more destructive than the bombs dropped on Japan in 1945. Warheads with a lower yield pose their own unique risks, in particular because they may be considered to be “more useable.” A president may be reluctant to use a bomb 80 times more destructive than the bomb that destroyed Hiroshima, but perhaps less so for a 2 or 3-kiloton bomb.

Presently, the U.S. has approximately 1,740 warheads deployed and ready to launch at any time, according to the Nuclear Information Project. These warheads make up the U.S.’s nuclear triad — the three means of delivering nuclear weapons: by land (Intercontinental Ballistic Missiles or ICBMs), air (dropped or fired from aircraft or bombers) and sea (fired from submarines).

Nuclear Weapons in Europe

Susi Snyder, a financial sector coordinator with the International Campaign to Abolish Nuclear Weapons (ICAN), specializes in untangling the complex web of public, private, and corporate firms and institutions that bankroll nuclear weapons. For Snyder, an American living in the Netherlands, nuclear weapons are not just a financial dragon to slay, they are an immediate and unwelcome neighbor.

Snyder points out that the U.S. has B61 gravity bombs deployed at six military bases in five NATO countries (Belgium, Germany, Netherlands, Italy and Turkey). The currently estimated 100 B61-3 and -4 series have adjustable yield options from 0.3 kilotons to 170 kilotons and 50 kilotons respectively that can be delivered by multiple NATO aircraft, F-15s and F-16s.

Four B61 variants are slated to be replaced with the B61-12, currently in production. When complete, the B61-12 will become the first variable yield guided nuclear gravity bomb. Designed to be more accurate, two of its four settings will be “low-yield” (0.3 and 1.5 kiloton), with options to dial-up to 10 and 50 kilotons. It will be deliverable by seven types of aircraft, including the F-35A Lightning II and the new $200 billion B-21 stealth bomber.

Snyder says the term “low-yield” is misleading because even the lowest yield nuclear weapon is tremendously destructive. In 2014, Snyder coauthored a report which considered the humanitarian consequences of a 12-kiloton nuclear weapon being detonated at Europe’s largest port facility in Rotterdam.

In addition to the 60,000 people estimated to be killed within hours or days, many more would be exposed to lethal doses of radiation. An unprecedented disruption of transportation and services throughout Europe would follow as a trail of radioactive fallout spread across the rural “green heart” of central Holland and decimated the Netherland’s vital agricultural sector.

ICAN recently published a report which describes the severe vulnerabilities of health care systems around the world following the detonation of a single 100-kiloton airburst nuclear weapon, a mid-range yield in the arsenals of several countries. The report presents a series of disturbing scenarios in which doctors, nurses, hospitals and urban populations would be utterly incapable of adequately responding to the effects of a single nuclear blast.

A Grim Prospect

Other researchers have considered the effects of much smaller nuclear detonations in urban settings. Eva Lisowski, a member of the Nuclear Weapons Education Project at the Massachusetts Institute of Technology and a nuclear science and engineering consultant in Tokyo, published her findings in two studies examining the possible impact of nuclear weapons being detonated on the Korean Peninsula and the Middle East. In “Grim Prospect: Low-Yield Nuclear Weapons in the Middle East,” Lisowski assesses the effects of a “low-yield” uranium device detonated at ground level in a densely populated city center with modern construction and population density.

Lisowski spent one year developing modeling exercises using population data, geographic information system (GIS) software and other data for five target cities: Tehran, Riyadh, Tel Aviv, Cairo and Dubai. In each case, the estimated deaths within 12 weeks from a 1-kiloton bomb detonated at ground level ranged from a low of 32,000 in Riyadh and 42,000 in Tel Aviv up to 137,000 in Tehran and 353,000 in Cairo. Lisowski details her findings at length in this review of her report.

In her simulations, she accounted for deaths due to bomb blast, heat, radiation, flying debris and structural collapse. Comparing a 1-kiloton blast to the September 11 attacks, she says, “It’s even more devastation. There’s going to be buildings coming down all over the place.”

“If you detonate at surface level, then the radiation, even in the city, can really have an effect. There could be death tolls that are comparable to Hiroshima and Nagasaki,” Lisowski told Truthout. “One kiloton is a yield that we have to care about.”

Beyond Comparison

When examining the roster of past and present nuclear weapons, it’s tempting to compare their destructive capacity with non-nuclear human-made or natural explosions, but it’s complicated. Following the Hunga Tonga undersea volcano eruption in January, scientists at NASA compared the power of the eruption to a 10-megaton blast, close to the size of the United States’ first thermonuclear test at Enewetak Atoll in 1952. But volcanos are not nuclear bombs and direct comparisons can be misleading.

Science and Security Board member of the Bulletin of the Atomic Scientists Steve Fetter says, “I think the best way to accurately compare the effects of nuclear weapons of various yields is to show the areas affected by various effects (blast, thermal, radiation) or over which various percentages of people would be killed or injured.”

He cautioned that comparisons between nuclear and other human-made or natural explosions are difficult. “Most importantly, nuclear (and other human-made) explosions are likely to kill more people than a natural explosion of far greater yield because they are far more likely to occur in or near densely populated areas.”

In 2020, when 2,750 tons of ammonium nitrate exploded at the port of Beirut, more than 7,000 people were injured and over 200 were killed. Cell phones captured the violent blast which displaced 300,000 people and damaged buildings 12 miles away.

Peter Goldstein, a physicist at Lawrence Livermore National Laboratory, studied the explosion and surrounding environment to reconcile varying estimates suggesting the blast may have been a few kilotons (or possibly much more) or it could have been as small as half a kiloton. Studying the size of the crater left by the explosion and seismic measurements, Goldstein concluded the chemical explosion was between 0.7 and 1.4 kilotons of TNT, significantly less than the 2.75 kilotons of material reportedly stored at the site.

One way to visualize what kind of damage a nuclear weapon can cause under specific conditions in a particular location, is with online simulators like Nuke Map and Outrider. Another is to read the findings of scientists and researchers who have examined the global impacts of a “limited” nuclear war between India and Pakistan.

But absent the tremendous roar, the blinding light, the painful wall of heat, the collapse of buildings, shattering of glass, and subsequent fires, blood, cries, and terrible darkening of the sky with soot, ash and smoke, the closest we can come to imagining a nuclear explosion is through the stories of hibakusha (nuclear survivors) who experienced it themselves in Japan, the Marshall Islands, Kazakhstan or within the United States.

From Deterrence to Intent to Use

Stephen Schwartz is a non-resident senior fellow at the Bulletin of the Atomic Scientists. Regarding the utility of more powerful nuclear weapons, he notes the irony that the U.S.’s largest nuclear weapon, the B83-1 gravity bomb, with a yield of 1.2 megatons, is considered too destructive to use. “In the minds of some, it would create too much devastation if used, and therefore, it would essentially be self-deterring,” Schwartz told Truthout. “We might, ourselves, decline to use it because it would destroy far more buildings and infrastructure and kill many more people than we had intended or desired.”

The idea that such a bomb could be used in battle is theoretical, what he called an “absurd state of affairs,” noting that, “we’ve never had a nuclear war. We’ve only used nuclear weapons twice and that was against a country that did not have nuclear weapons that it could fire back at us.”

Contrary to the oft-repeated 1985 joint Soviet-U.S. statement that “a nuclear war cannot be won and must never be fought” (a declaration at least nominally reaffirmed by the original five nuclear weapons states earlier this year), the U.S. is investing heavily in “more usable” lower-yield nuclear weapons like the W76-2 and B61-12, a trend Schwartz calls a “huge problem” because it marks a shift from using nuclear weapons to deter to instead using them with the intent to fight.

If the Biden administration withdraws plans to further develop the W76-2, Schwartz says it would send a message that the U.S. is less interested in fighting a nuclear war than in trying to prevent one.

“We, in fact, are the ones that are moving with this W76-2, with the B61-12 which isn’t deployed yet, and with other strategies to make nuclear weapons more useable,” Schwartz says.

Does he think it’s possible nuclear weapons could be used?

“Yes, that’s the whole unfortunate essence of nuclear deterrence. You are prepared to utterly annihilate the world in order to prevent the world from being annihilated.” He adds, “We can speculate all we want about this, but the reality is that we are fully prepared, as is Russia, to use nuclear weapons 24 hours a day, seven days a week.”

Hard to Dismantle an Atomic Bomb

Melissa Hanham, an independent analyst and affiliate of Stanford’s Center for International Security and Cooperation, sees the greatest risk of nuclear weapons being used coming from a misunderstanding, miscalculation or accident. She says those risks can be reduced through the robust pursuit of arms control and diplomacy, adding that another important measure nuclear-armed states can take is to reduce stockpiles, starting with weapons deemed no longer necessary for specific missions.

Hanham points out that although there is acceptance from disparate quarters that both Russia and the U.S. can continue to reduce their overall nuclear stockpiles, mustering the political fortitude to do so remains elusive. For politicians to initiate a reduction in nuclear forces, there needs to be a political incentive backed up by sustained and strong public support.

One under-appreciated problem stemming from nuclear weapons is what to do with them once they are slated to be retired and dismantled. Hanham says we need to pay greater attention to logistical, technical and scientific challenges inherent in dismantling nuclear warheads.

She says it’s time to do the hard work of taking nuclear weapons apart, particularly those deemed no longer needed. Obstacles to doing so remain large, funding for research has dwindled, and it’s difficult to capture the public’s attention.

“In my generation, it’s not cool to build nuclear weapons anymore. No one wants to study how to do that, but you also need to know how to take them apart. These weapons were designed … with the intent of sending the political message that they will be used, not disassembled,” Hanham told Truthout.

Disassembly requires not only highly technical knowledge, but also specialized tools and secure facilities to do so. That technical expertise remains in older generations and isn’t trickling down, Hanham says, it’s atrophying.

“We literally have to design the tools to take them apart. You can’t just take a screwdriver and take it apart,” Hanham says. “And it’s expensive. Up front, it’s a lot of money. In the long run, maintaining that many weapons costs more.”

Today, the U.S. has around 1,720 nuclear weapons retired or waiting dismantlement and the Federation of American Scientists’ Korda says that rate has been slowing in recent years.

Both nuclear weapons assembly and dismantlement happens primarily at the Pantex Plant in Amarillo, Texas, with secondary activities taking place at the Y-12 National Security Complex in Oak Ridge, Tennessee; Savannah River Site, South Carolina; and Kansas City National Security Campus in Missouri. National Laboratories also play a central role in the U.S.’s nuclear weapons enterprise.

As society’s overall perception and understanding of nuclear weapons is diluted and fades, Hanham worries about a public that increasingly thinks of nuclear weapons as simply being much bigger and more powerful.

“Nuclear weapons are a completely different animal than an artillery rocket or conventional warhead,” she says. “Nuclear weapons are the most awful, most terrible weapon ever invented, and I do think it’s useful for humans to feel that seismic shift from what is just a large weapon to what is an existential threat to the existence of humans.”

Meanwhile, in the absence of significant mainstream media scrutiny or sustained public opposition, the United States continues to invest heavily in modernizing its nuclear weapons, both large and small. But, as Hanham says, “you can’t just nuke someone a little bit … once you start a nuclear war, it’s on.”