Over the coming fifteen years, the Pentagon plans to spend many billions of dollars modernizing the strategic nuclear triad—when the defense budget faces competing demands. On June 14, Secretary of Defense James Mattis indicated to a Senate Appropriations subcommittee that he had not yet made up his mind about the Long-Range Standoff (LRSO) weapon, a new nuclear-armed, air-launched cruise missile. He should think carefully, as a convincing case for the LRSO has not been made.
To be sure, the United States needs to modernize its triad. Building Columbia-class ballistic-missile submarines to replace aging Ohio submarines, a new intercontinental ballistic missile (ICBM) to replace the Minuteman III, and the B-21 strategic bomber make sense—though one can question the planned numbers. The 1,550 deployed strategic warheads that the 2010 New Strategic Arms Reduction Treaty (New START) allows to the United States could be carried on fewer strategic delivery vehicles, of which the United States has significantly more than Russia.
The arguments for the LRSO, however, are not compelling. The Air Force developed air-launched cruise missiles (ALCMs) in the 1970s due to concern that the B-52 presented a large target on Soviet radar screens and could not penetrate increasingly sophisticated Soviet air defenses. B-52s armed with nuclear-armed ALCMs had no need to penetrate; they could launch their cruise missiles from well outside of Soviet airspace (in those days, the Air Force did not have conventional standoff weapons).
Things have changed. The B-2 was the first U.S. stealth bomber. The B-21 will have both stealth and advanced electronic-warfare capabilities to deal with adversary radars. It is intended to operate in contested skies. Moreover, in order to arm the B-21 and other aircraft, the Department of Energy is producing a new variant of the B61 gravity bomb that will be highly accurate and have a variable yield of 0.3 to 50 kilotons. The Air Force does not need the LRSO to have a variable-yield weapon.
If the B-21 can penetrate sophisticated air defenses and deliver an accurate weapon with a low yield, the LRSO seems redundant. Moreover, the B-21 will get a standoff capability with conventional cruise missiles. Canceling the LRSO and its nuclear warhead could produce significant savings, in the range of $15–30 billion. (LRSO advocates would assert that the cost of the program over a thirty-year lifetime is a small fraction of total defense spending. True, but one can say that about every major Defense Department weapons purchase. Those “small fractions” add up to bust the budget.)
Some argue that the LRSO is necessary to equip the B-52 as the current ALCMs are retired around 2030. By that time, however, there should be a number of B-21 bombers to take on the nuclear mission. The remaining B-52s (which at that point will be almost seventy years old) could shift to conventional missions, as have other B-52s.
Exactly which target, or set of targets, could the LRSO hold at risk that other weapon systems—submarine-launched ballistic missiles (SLBMs), ICBMs, or B-2 and B-21 bombers armed with B61 bombs—could not?
Others note that the LRSO will be faster than a B-21 with a gravity bomb, which would have to overfly or get close to the target. For most long-range missions, however, the time savings would be marginal. The B-21 would still have to haul the LRSO most of the way. If a mission were time sensitive, the military would have to use an ICBM or SLBM.
It seems that the strongest argument LRSO supporters can muster is that the B-21 might not be able to operate in a contested air-defense environment. If that is truly a problem, it would be more logical to go forward with the LRSO and cancel the B-21, replacing it with a less expensive nonstealth bomber to launch LRSOs offshore. And yet, the Air Force maintains its faith in the stealth and electronic-warfare attributes of the B-21.
At a minimum, it would make sense to delay procurement of the LRSO until such time—if ever—as the B-21’s survivability appears to be coming into question, and the Pentagon concludes that the targets cannot be held at risk with other nuclear weapons. Delaying procurement would reduce the large “bow-wave” of spending requirements for strategic force modernization in the mid-2020s.
A related issue is the number of LRSOs the Air Force wishes to procure: 1,000–1,100. That looks like a significant increase in the number of air-launched cruise missiles available for bomber missions. While the Air Force does not say how many ALCMs or nuclear gravity bombs it deploys for its bombers, there are strong clues.
The 2002 Strategic Offensive Reduction Treaty (SORT) limited the United States and Russia each to no more than 1,700–2,200 operationally deployed strategic nuclear warheads. While the treaty did not define an operationally deployed strategic nuclear warhead (one of its many shortcomings), the U.S. government had its definition: ballistic-missile warheads on SLBMs and ICBMs plus the number of bomber weapons—ALCMs and gravity bombs—kept in storage areas at nuclear-capable-bomber bases.