The head of U.S. Strategic Command (STRATCOM) and the top U.S. Air Force deterrence official defended the intercontinental ballistic missile (ICBM) leg of the nuclear triad in separate forums on Apr. 22 by saying that ICBMs are needed to execute the National Command Authority”s scope of deterrence missions and to act as a hedge against the possible unavailability of the other two legs—the U.S.’ 14 Ohio-class ballistic missile submarines (SSBNs) and bombers, which have been off of nuclear alert since 1991.

The 2018 Nuclear Posture Review stated that “ballistic missile submarines are the most survivable leg of the triad” and that “when on patrol, SSBNs are, at present, virtually undetectable, and there are no known, near-term credible threats to the survivability of the SSBN force.” The review said, however, that the U.S. “will continue to hedge against the possibility that advances in antisubmarine warfare could make the SSBN force less survivable in the future.”

Asked on Thursday why the ICBM leg was needed–either a service life extension of the 400 Boeing [BA] Minuteman III missiles or a purchase of the next generation Northrop Grumman [NOC] Ground Based Strategic Deterrent (GBSD), STRATCOM Commander Adm. Charles Richard pointed to current presidential guidance to be able to execute nuclear war plans and to the history of such plans.

“First, there is a total amount of capability and capacity that’s required to execute the responsibilities that I have been given,” Richard said. “I need the forces that we have to include the intercontinental ballistic missiles to be able to accomplish all of that. We don’t have capacity in any to start to change that unless we change the guidance, right? We can always do that.”

“The second piece is there are things that we all take as givens nowadays,” Richard said. “One of them is ‘bolt out of the blue’—an unwarned, large attack. I think we would all agree that that is highly unlikely. We’d be the first to tell you that it’s highly unlikely because we look at it every day, but we forget how we got here in some cases. We made ‘bolt out of the blue’ unlikely [through] ballistic missile submarines, the responsiveness of the intercontinental leg, our postures, our policies, the way we execute. The reason ‘bolt out of the blue’ is unlikely is because it’s probably not going to work, and so we have to be careful when we make future decisions that we don’t forget how we got here lest we return ourselves to a world we don’t want to be in.”

The Biden administration is reviewing nuclear policy, and some defense analysts believe that the White House may significantly alter the triad and cut GBSD.

On Apr. 22, Air Force Lt Gen James Dawkins, the service’s deputy chief of staff for Strategic Deterrence and Nuclear Integration, told a Mitchell Institute of Aerospace Studies’ forum that, while he knows of no near-term threats to the U.S. SSBN force, “I can’t predict the future.”

“I think trying to make assumptions what the future is going to look like in the next 30 years with regard to vulnerabilities is short-sighted,” he said. “I think it’s a small price to pay to have the ICBMs available as an insurance policy, not only ICBMs, but the bombers, and the stand-off cruise missiles that accompany the bombers, as well as the very important submarine part of the deterrent. I think that’s key. All those contribute to strategic stability.”

While DoD officials often speak of the Russian nuclear threat and advances in Chinese nuclear capabilities as reasons to continue the nuclear triad, a 2012 DoD and intelligence community study obtained under the Freedom of Information Act (FOIA) by Hans Kristensen, director of the Nuclear Information Project at the Federation of American Scientists (FAS), suggests that U.S. SSBNs underpin strategic stability.

If the Russians were to deploy a significant number of additional nuclear warheads, such deployment “would have little to no effect on the U.S. assured second-strike capabilities that underwrite our strategic deterrence posture,” per the study. “The Russian Federation, therefore, would not be able to achieve a militarily significant advantage by any plausible expansion of its strategic nuclear forces, even in a cheating or breakout scenario under the New START Treaty, primarily because of the inherent survivability of the planned U.S. strategic force structure, particularly the Ohio-class ballistic missile submarines, a number of which are at sea at any given time.”

In an Apr. 22 email, Kristensen wrote that the leadership for any change to the nuclear triad, including an ICBM cut, “will have to come from the White House.”

“STRATCOM, of course, can’t say that it doesn’t need the ICBMs,” Kristensen wrote. “The ‘bolt out of the blue’ is not just about keeping everything we have – that because we haven’t had such an attack, nothing can change.”

The flexibility/”hedge” arguments made for the nuclear triad in the 2018 NPR and in DoD circles are “standard nuclear theology,” per Kristensen.

“There are three legs. All are unique. All are indespensible. Nothing can change,” he wrote. “There is no evidence offered for these claims. We used to have nuclear weapons on aircraft carriers, and there were submarine-launched land-attack cruise missiles, just to mention a few. Everything was needed for flexibility and back-up. Nothing could change until a president said it should, and then it changed.”

“If Biden changes the guidance and cancels the GBSD and instead extends the life of 200 of the Minuteman IIIs, then STRATCOM and the Air Force will say that’s just what’s needed,” Kristensen wrote. “I’m somewhat cynical about these [necessity of the nuclear triad] claims. I’ve heard them too often, and they only last until the next decision.”