The United States will decommission the B83-1 thermonuclear gravity bomb, which is the country's most powerful atomic warhead, according to the US national defense strategy published by the Pentagon. 

"The B83-1 gravity bomb will be retired due to increasing limitations on its capabilities and rising maintenance costs," the document, published on Thursday, said.

The US plans to use other existing opportunities in order to "hold at risk hard and deeply buried targets," the strategy said, adding that the defense ministry will develop a new tool, "working with its interagency partners and informed by existing concepts." 

In the late 1970s, the US developed the free-falling B83 thermonuclear aerial bomb that yields 1.2 megatons of energy. For comparison scale, the atomic bombs which targeted Hiroshima and Nagasaki in August 1945 were around 15 and 25 kilotons respectively. 

Citing diplomatic cables and other sources, Politico claimed on Thursday that the US hastened the deployment of a modernized B61-12 nuclear weapon at NATO bases in Europe, with a target date of the end of 2022 instead of 2023.

The modernized B61-12 atomic bomb's initial manufacturing sample was reportedly delivered to the Department of Defense by the US military-industrial complex in December 2021. Since 1968, the B61 aerial bomb has undergone several upgrades. The upgraded bomb can be dropped from the F-15, F-16, F-35, and Tornado, as well as the B2 and B-21 strategic bombers.