Pentagon looks to produce nuclear gravity bomb 24 times larger than bomb dropped on Japan

The Defense Department said that pending congressional approval, it will produce a new nuclear gravity bomb with a warhead yield 24 times larger than the "Little Boy" bomb dropped on Hiroshima, Japan, near the end of World War II. 

"The United States has a responsibility to continue to assess and field the capabilities we need to credibly deter and, if necessary, respond to strategic attacks, and assure our allies," Assistant Defense Secretary for Space Policy John Plumb said last week when the new bomb was announced.

The bomb, known as a B61-13, would replace some of the B61-7 bombs in the U.S. arsenal, and it would have a similar yield to the B61-7s. The bomb would have the same safety and accuracy features of the B61-12 while having a higher yield, according to officials.

"While it provides us with additional flexibility, production of the B61-13 will not increase the overall number of weapons in our nuclear stockpile," Plumb also said. 

The bombs that the B61-13s would replace, the B61-7s, have a maximum yield of 360 kilotons, according to the Federation of American Scientists. This is 24 times more powerful than the 15 kiloton bomb that was dropped on Hiroshima and killed at least 70,000 people, per the Bulletin of the Atomic Scientists. 

For comparison, if Little Boy were to be dropped in the same manner over lower Manhattan today, more than 260,000 people would die, according to the simulator Nukemap. If the proposed B61-13 were dropped in the same place, more than 1.1 million people would die. 

The Pentagon stressed that the proposal of the new bomb "is not in response to any specific current event" but that "it reflects an ongoing assessment of a changing security environment."

The announcement comes amid rising tensions between the West and Russia, North Korea, China and Iran. 

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