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US plans to build new ‘nuclear gravity bomb’ 24 times powerful than Hiroshima nuke


The proposal is “pending with Congressional authorisation and appropriation”, it said. If approved by the Congress, the B61-13 will replace the 1980s era B61-7, the US department said in a press release published on October 27, 2023.

What are nuclear gravity bombs?

Gravity bombs work by being pulled to the ground by the force of gravity instead of flying to the target on a powered missile, New York City-based Vice News reported. In this case, a bomber or an aircraft flies over the target and drops the bomb.

“These bombs do not consist of a guidance system and, hence, follow a ballistic trajectory,” Eurasian Times reported.

ALSO READ: A new nuclear arms race looms

What are US B61 bomb variants?

The B61-13 will be the latest in a long line of B61 variants.

The US Department of Defence said the B61-13 will replace some of the B61-7s in the current stockpile.

It will have a yield similar to the B61-7, which is higher than that of the B61-12, stated the factsheet shared by the US department.

The factsheet added that the B61-13 will include the modern safety, security, and accuracy features of the B61-12.

ALSO READ: India prioritising longer-range nuclear weapon that can reach China; Pakistan remains primary focus: Report

How powerful are B61 nuclear gravity bombs

“The new bomb (B61-13) will have the same yield as the old (B61-7) which is estimated to be 360 kilotons, roughly 24 times bigger than the blast that destroyed Hiroshima,” Vice reported.

The two bombs that the US dropped on Japan’s Hiroshima and Nagasaki during World War II in 1945 were significantly less powerful. “The Hiroshima bomb was of about 15 kilotons – that is, of 15 thousand tonnes (or kilotons) of TNT equivalent – and that at Nagasaki was of 25 kilotons (ca. 65 and 105 GJ respectively),” according to the World Nuclear Association.

According to a report, the maximum yield of the B61-12 is 50 kilotons. The warhead reportedly had options, including 0.3kt, 1.5kt, 10kt, and 50kt.

Why US chose to build a new nuclear weapon

In 2022, a US report alleged that China was involved in rapid nuclear expansion. The Department of Defence “estimated that the People’s Republic of China (PRC) possessed more than 500 operational nuclear warheads as of May 2023—on track to exceed previous projections”.

It further estimated that the “PRC will probably have over 1,000 operational nuclear warheads by 2030”.

Meanwhile, Russian President Vladimir Putin signed into law, pulling Russia out of the global treaty banning nuclear weapons tests. The step was condemned by the US and the organisation that promotes adherence to the landmark arms control pact, the Guardian reported.

In the press release, the US explained that the latest decision to pursue the nuclear capability “responds to the demands of a rapidly evolving security environment as described in the 2022 Nuclear Posture Review”.

“Today’s announcement is reflective of a changing security environment and growing threats from potential adversaries,” said Assistant Secretary of Defense for Space Policy John Plumb.

It added that the B61-13 will provide the “President with additional options against certain harder and large-area military targets, even while the Department works to retire legacy systems such as the B83-1 and the B61-7”.

However, the US clarified that “the fielding of the B61-13 is not in response to any specific current event; it reflects an ongoing assessment of a changing security environment”. This statement came at a time when Israel and Russia are involved in a war with Hamas and Ukraine respectively.

The Pentagon further informed that the B61-13 won’t change the size of the nuclear stockpile. “The B61-13 will not increase the overall number of weapons in the U.S. stockpile. The number of B61-12s to be produced will be lowered by the same amount as the number of B61-13s produced,” it said.

Who has more nuclear weapons: Russia Vs China Vs US

According to the data by the World Population review, as in 2023, Russia leads with 6,257 weapons’ (1,458 active, 3039 available, 1,760 retired).

The US is at the second position with 5,550 nuclear weopons (1,389 active, 2,361 available, 1,800 retired); and China is at third with 350 available nuclear weapons’.

Meanwhile, the Arms Control Association puts the tally at 5,889 for Russia, 5,244 for the US and 410 for China. 

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Updated: 05 Nov 2023, 04:50 PM IST

Joanna Swanson

Joanna Swanson is Europe correspondent at the Thomson Reuters Foundation based in Brussels covering politics, culture, business, climate change, society, economies and inclusive tech. With specific focus in breaking news, she has covered some of the world's most significant stories.