PERSPECTIVE: NUCLEAR ESCALATIONThe Smaller Bombs That Could Turn Ukraine into a Nuclear War Zone

Published 22 March 2022

The nuclear weapons in the arsenals of Russia and NATO countries have much smaller yields than the large bombs built during the Cold War. These warheads are even smaller than the bombs dropped on Hiroshima and Nagasaki. William Broad writes that it is this much lower yield which makes their use more thinkable.

On 30 October 1961, over the remote arctic island of Nova Zemlya, the Soviet Union detonated the largest nuclear bomb ever built. At 50 megatons, the bomb was 3,800 more powerful that the nuclear bomb the United States dropped over Hiroshima.

The U.S. largest nuclear detonation took place on 1 March 1954 at the Bikini Atoll – and it was the result of a scientific error. The Loa Alamos scientists assembling the bomb missed an important fusion reaction, resulting in a gross underestimation of the size of the explosion. The test was meant to be of a bomb with a yield of 5 megatons, but the actual explosion was three times more powerful. At 15 megatons – 1,000 more powerful than the Hiroshima bomb – it was the largest U.S. nuclear test.

William J. Broad writes in the New York Times that today, both Russia and the United States have nuclear arms which are far less destructive, with their power being just fractions of the Hiroshima bomb’s force.

It is this much lower yield which makes their use more thinkable.

Broad adds:

Concern about these smaller arms has soared as Vladimir V. Putin, in the Ukraine war, has warned of his nuclear might, has put his atomic forces on alert and has had his military carry out risky attacks on nuclear power plants. The fear is that if Mr. Putin feels cornered in the conflict, he might choose to detonate one of his lesser nuclear arms — breaking the taboo set 76 years ago after Hiroshima and Nagasaki.

Analysts note that Russian troops have long practiced the transition from conventional to nuclear war, especially as a way to gain the upper hand after battlefield losses. And the military, they add, wielding the world’s largest nuclear arsenal, has explored a variety of escalatory options that Mr. Putin might choose from.

“The chances are low but rising,”  Ulrich Kühn, a nuclear expert at the University of Hamburg and the Carnegie Endowment for International Peace, told Broad. “The war is not going well for the Russians,” he observed, “and the pressure from the West is increasing.”

In 2018, Dr. Kuhn wrote a study – Preventing Escalation in the Baltics: A NATO Playbook – in which he laid out a crisis scenario in which Russia detonated a bomb over a remote part of the North Sea as a way to signal deadlier strikes to come.

He told Broad that, in a similar fashion, Putin might fire a weapon at an uninhabited area instead of at troops. “It feels horrible to talk about these things,” Dr. Kühn said in an interview. “But we have to consider that this is becoming a possibility.”

Military experts say that the United States might respond to a small Russian nuclear blast by firing a nuclear-tipped cruise missile from a submarine into the wilds of Siberia, or at a military base inside Russia to signal to Russia that NATO was not going to back down. The burden of how to respond to NATO’s retaliation will then be Putin’s, who would have to consider whether he wants to engage in a tit-for-tat escalation which might get out of hand.

Nina Tannenwald, a political scientist at Brown University. Told Broad that she was wondering whether the old protections of nuclear deterrence, now rooted in opposing lines of less destructive arms, would succeed in keeping the peace.

“It sure doesn’t feel that way in a crisis,” she said.