The B61-12 nuclear bomb is now formally in the U.S. stockpile and cleared for operational use on the B-2A Spirit stealth bomber. It's the first U.S. combat aircraft cleared to employ the advanced B61 variant operationally.

U.S. Air Force F-35A Joint Strike Fighters, F-15E Strike Eagles, and F-16C/D Vipers, as well as the service's future B-21A Raider stealth bombers, are also in the process of being certified to employ the B61-12. Some NATO F-35s and F-16s, as well as Germany's swing-wing Tornado combat jets, are also set to be cleared to employ these weapons as part of the alliance's nuclear sharing arrangements.

The updates about the B61-12, among other items of interest, are contained in a new unclassified Stockpile Stewardship and Management Plan (SSMP) report for the 2024 Fiscal Year that the National Nuclear Security Administration (NNSA) released earlier today. NNSA, part of the Department of Energy, oversees America's nuclear stockpile in coordination with the U.S. military.

The B61 series are some of the longest-serving nuclear weapons in the U.S. stockpile. The B61-12 has been slated to eventually supplant existing B61-3, -4, and -7 variants, but more later.

The first production B61-12 was completed in late 2021 and the weapons began being delivered to the U.S. military in 2022. The B61-12 program, which is technically a life-extension effort, is currently slated to wrap up in Fiscal Year 2025.

The B61-12 is not an entirely new weapon, and leverages components from multiple existing B61 types while also combining them with various new and improved features. The most significant new capability found on the B61-12, each of which famously costs more than its literal weight in gold, is its precision guidance package. However, this functionality will not be usable when the weapon is employed from F-16s belonging to the Air Force and select NATO member countries, as well as German Tornados. You can read more about all this here.

The B61-12, which also has small rockets at the rear of the body that spin the bomb to help stabilize it, is a so-called dial-a-yield bomb that can be set to detonate with various degrees of explosive force. Its reported maximum yield setting is 50 kilotons. This is similar, if not identical to what is understood to be the highest yield setting on the B61-4 (45-50 kilotons, depending on the source).

Flight testing of the B61-12 on the B-2, as well as other aircraft, has been ongoing for years now. Back in 2018, when the bomb was still in development, NNSA announced it had completed an initial round of end-to-end qualification flight tests on the B-2.

In June of that year, a B-2 conducted another test demonstrating the ability of the bomber to employ the weapon using the Radar Aided Targeting System (RATS).

"RATS improves weapon guidance accuracy in a Global Positioning System-degraded environment," the Air Force said at the time.

"The integration of RATS allows the B-2 to fully employ the B-61 mod 12 nuclear bombs," Northrop Grumman, the B-2's manufacturer, which remains responsible for the continued modernization and sustainment of the bombers, said in a subsequent press release in August 2022. "RATS is the key element of the nuclear modernization, as GPS may not be available during a bomber task force mission."

The timeline for when the B61-12 will be approved for use with the F-35, F-15, F-16, or any NATO aircraft is unclear. NNSA and the U.S. Air Force have previously announced initial certification of the B61-12 on the F-15E and the F-35A. The Royal Netherlands Air Force publicly announced earlier this month that it had reached a similar milestone with its F-35As.

NNSA's new SSMP report says the B-2's nuclear armament options also still include the B61-7, B61-11, and B83-1 nuclear bombs. The Spirit is actually currently the only aircraft approved to employ any of these bombs. The B61-7 is a higher-yield variant of the B61 family, which can reportedly be set to detonate with a force of up to 400 kilotons. The B61-11 is a highly specialized deep-penetrating version with a maximum yield similar, if not the same as the B61-7. You can read more about the entire B61 family in detail in this past War Zone feature.

The B83-1 is a completely different design with a megaton-class maximum yield.

The B61-11 and B83-1 are primarily intended to be utilized against deeply buried and otherwise hardened high-value targets, such as strategic command and control bunkers and missile silos. President Barack Obama's administration had moved to retire the B83-1 completely, a decision that was then reversed under President Donald Trump.

President Joe Biden's "2022 Nuclear Posture Review directed the retirement of the B83-1" again, but "specific details of the B83-1 retirement and dismantlement plan remain classified," according to NNSA's latest SSMP report.

There had previously been discussion about the possibility of the B61-12 replacing the B61-11 and the B83-1 through its ability to focus the full brunt of its lower-yield payload more precisely, thanks to its guidance kit and spin stabilization. However, that idea now looks to have given way to a new version of the B61 with all the new and improved features of the B61-12 but a maximum yield equivalent to that of the B61-7. Last month, the Pentagon announced its intention to develop this B61 variant, tentatively dubbed the B61-13tentatively dubbed the B61-13.

"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," an official fact sheet explained. No mention was made of any plans to retire the B61-11.

The B61-13 plan, which still requires approval from Congress, would also see the expected stockpile of B61-12s shrink to some degree. The balance would, instead, be made up of some number of higher-yield -13 versions. The total numbers of B61-12s and B61-13s the U.S. military wants to acquire under this new course of action are classified. You can read more about what is known about the B61-13 and the reasoning behind its proposed development and acquisition here.

All of this will also have impacts on what nuclear bombs are available in the future for the Air Force's forthcoming B-21A bombers. The Raiders will likely be able to employ the same slate of nuclear bombs, as long as they're still in the stockpile, as the B-2A. The B61-13 is also expected to be for U.S. military use only, unlike the B61-12. The elimination of the B83-1 and B61-7 would leave only B61-11, 12, and 13s as the only nuclear gravity bombs in the U.S. stockpile at all.

It's also worth noting that the B-52H is no longer authorized to carry any nuclear gravity bombs of any type, with the understanding that it is too vulnerable to actually get to the kind of heavily defended targets against which they would be employed. Instead, the only known current and future nuclear weapon options for those bombers, which are set to keep flying at least into the 2040s with the help of new engines and other major upgrades, will be nuclear-tipped cruise missiles. The existing AGM-86B Air Launched Cruise Missile (ALCM) will eventually be replaced by the more capable AGM-181A Long Range Stand-Off (LRSO) cruise missile. LRSO is expected to enter service sometime in the 2030s and will also be integrated onto the B-21A.

Altogether, what the exact mix of nuclear weapons available for employment from U.S. Air Force aircraft, as well as those belonging to select NATO partners, will be in the 2030s remains to be seen.

What we do know is that the B61-12 is now officially in the U.S. stockpile and that B-2 stealth bombers can drop them in anger.

Let's hope this capability is never tested in combat.