The B61-13
Last month, the Department of Defense announced that it will pursue a new version of its B61 nuclear gravity bomb, dubbed the B61-13. The “13” designation reflects that the variant will be the thirteenth variant of the bomb, first designed in 1963. In the DoD’s press release, Assistant Secretary of Defense for Space Policy John Plumb stated that the new decision is “reflective of a changing security environment and growing threats from potential adversaries.” The new bomb specifically strengthens deterrence “by providing the President with additional options against certain harder and large-area military targets.”
The bomb will not increase the total number of weapons in the United States’ nuclear arsenal, instead replacing B61-12s that are currently in production. It will have a similar yield to the existing B61-7 (variable from 10 to 360 kilotons). For comparison, the B61-12s will have a maximum yield of 50 kilotons, much lower than the 13’s potential maximum. This raises the question of why such a large yield is needed. What have independent experts said about the Pentagon’s given rationale for the new bomb? Will it give the United States a significant new military capability?
The Center for Arms Control and Non-Proliferation has argued that the “need” for the B61-13 is “nebulous at best.” It makes the case that over the past twenty years, planners have moved away from high-yield nuclear weapons due to improving accuracy and the development of conventional alternatives. Why the new weapon, then? Experts at the Federation of American Scientists (FAS) argue that the new bomb is part of a political deal to ensure that the B83-1 can be retired, which is the last megaton-yield weapon remaining in the U.S. arsenal (1 megaton is 1000 kilotons). For context, the B83 is eighty times more powerful than the bomb used to destroy Hiroshima at the end of World War II. The Obama administration favored retiring it, the Trump administration decided to retain it, and last year Congressional Republicans criticized the return of plans to retire it. If the plans for the B61-13 and the existing B83 are linked politically, this is certainly a different case than if the new program was evaluated as a military necessity (or at least as worth the cost). So does the B61-13 have a strong rationale for its development and use, militarily?
FAS experts say that the military does not need an additional, more powerful gravity bomb. This is because the “military mission” of nuclear gravity bombs is less important due to the risk of putting bombers (and their crews) in danger over “heavily defended targets.” As for alternatives, the military has many other types of nuclear weapons, including land-based and submarine-launched ballistic missiles. A new nuclear-armed air-launched cruise missile, called the LRSO or “long-range standoff” missile, is also under development. In fact, the LRSO will be deployed on the same strategic bombers that would carry the B61-13. It is difficult to see why a gravity bomb that necessitates greater risk for pilots would be a better operational choice than the cruise missile. There is the question of explosive yield, although the yield of the new warhead slated to be used with the LRSO is unknown, making it hard to compare. But with so many alternatives, a new program should require compelling reasons to justify developing and fielding it. Does the relatively high yield of the B61-13 make one such reason?
For the layman, a good way to conceptualize the yield, or explosive force, of a nuclear weapon is to use the online tool NUKEMAP. It allows you to input a location and view the casualties and radioactive fallout reach created by warheads of various yields. Using this tool illustrates the difference that an increase in yield gives strategists and planners. The high yield of the B61-13 means that it has huge destructive potential. However, with the United States already having thousands of nuclear weapons, how much additional deterrent value does this variant contribute? Given the limited military utility of the gravity bomb as described in this post, the deterrent effect is also questionable. Adversaries may doubt that the new bomb will actually be used during a conflict. So, the high yield of the B61-13 does not justify its development.
Whether the new B61-13 decision is primarily politically driven will likely not be admitted by civilian or military officials. But another important set of considerations is cost and resources. The United States is producing new submarines, bombers, and silos (replacing all three triad legs) to support its nuclear force posture. The NNSA (National Nuclear Security Administration) production schedule is full, as it needs to develop the capacity to produce new plutonium pits, while extending the life of existing warhead designs. The Congressional Budget Office projects the cost of U.S. nuclear forces at $756 billion for the next decade, a rise of about 20% from the 2021 estimate. With existing programs already at risk of delays and cost overruns, the B61-13 program will add further stress to the system’s capacity.
With experts skeptical of the B61-13 program’s necessity or usefulness, the decision to pursue its development should be re-evaluated. Instead of getting a political replacement by way of compromise, the B83 should also be evaluated in terms of its military capability and cost. War strategies are ultimately political decisions. However, the development of individual weapons or systems should not be driven by politics. We certainly should not be looking at invented justifications that cover for political compromises that are not based on requirements for our national security or those of our allies.
