US Nuclear Weapons Expert on Low-Yield Warheads, Stockpile Stewardship, and Plutonium Pit Production

Vice Admiral Dave Kriete explains how the United States maintains its stockpile, and why the nation is developing new low-yield nuclear weapons

7 min read

Vice Adm. Dave Kriete, who is the Deputy Commander of U.S. Strategic Command, speaks at Offutt Air Force Base in January 2019, in Omaha, Nebraska.
Vice Adm. Dave Kriete, who is the Deputy Commander of U.S. Strategic Command, speaks at Offutt Air Force Base in January 2019, in Omaha, Nebraska.
Photo: Ryan Soderlin/Omaha World-Herald/AP

Earlier this year, at a sprawling complex in the Texas Panhandle, a new type of nuclear weapon began rolling off the production line and into the United States arsenal. The ballistic missile warheads are low-yield and relatively small, and they reflect a growing push by U.S. President Donald Trump’s administration to modernize the nation’s nuclear weapons program after decades of stagnation.

Vice Admiral Dave Kriete has played a key role in developing U.S. nuclear weapons policies. Since June 2018, he has served as deputy commander of U.S. Strategic Command, the military unit responsible for detecting and deterring nuclear, space, and cyber attacks against the United States and its allies. Kriete also helped craft the 2010 and 2018 Nuclear Posture Reviews—the Pentagon’s guiding document for U.S. nuclear policy, strategy, and capabilities.

Kriete, who is based in Omaha, Nebraska, spoke with Spectrum during a recent visit to New York City. He discussed plans for nuclear weapons modernization, and the challenges to achieving them. This conversation has been edited and condensed for clarity.

Vice Adm. Kriete on…

IEEE Spectrum: How did international politics shift between 2010 and 2018, and how did that influence the outcome of the latest Nuclear Posture Review (NPR)?

Kriete: One of the assumptions made in the 2010 NPR was that Russia is our friend, and if the United States leads the world in reducing the roles or numbers of nuclear weapons, and their prominence in our national security policies, then the rest of the world would follow. It’s a very noble goal. But the intervening eight years proved to be very difficult because every other country that has nuclear weapons that could potentially threaten the United States or our allies did exactly the opposite.

While the United States actually did reduce the numbers and some of the types of systems, Russia greatly increased their number of nuclear weapons, the means that they have to deliver them, and most importantly, the prominence that nuclear weapons play in their military doctrine. As the United States implemented the Strategic Arms Reduction Treaty (START), Russia continued to develop a whole range of systems that were outside the treaty. [The treaty requires both sides to limit the number of deployed strategic nuclear warheads to no more than 1,550.]

Although China is not governed by START, or any arms control treaty, we saw China increase their number of nuclear weapons, and not only develop new delivery systems but also increase the capability of those systems in terms of accuracy, yield, and some of the technical characteristics. North Korea developed not only a nuclear weapons capability but also, throughout 2017 and 2018, a whole number of ballistic missile launches of various ranges. They made it clear that their capabilities could threaten not only other countries in the region, but that they had goals of threatening the United States, as well.

IEEE Spectrum: What are some key takeaways from the 2018 Nuclear Posture Review?

Kriete: The first and most important thing is to get on with nuclear force modernization. And we’re doing just that. 

The submarines; the long-range bombers that can literally fly around the globe; the intercontinental ballistic missiles (ICBMs) that are spread across the northern tier of the United States—each of these were really designed for a finite service life—some, 10 years, some, 20 years. They’ve all been in service far beyond that original design service life.

If you were going to sketch this out as an engineer, you would probably come up with a scheme to replace them sequentially, so you didn’t have to load all the effort into one period of time. But unfortunately that’s where we find ourselves today.  

Three programs to replace the nuclear triad—subs, the ICBMs, and the bombers—are all underway. And then we also have a program to replace the air-launched cruise missile, which is hosted on those bombers that have a global reach. We’ve recently begun an effort to shape how we’re going to replace those nuclear command and control systems that support all three legs of the triad in the future.

"The idea of radiation-hardened microelectronics is not something many other industries work on."

Although the physics of nuclear weapons is really unchanged, there are a lot of non-nuclear components that support the weapons. As we replace both the delivery systems and the warheads themselves, there’s been great advances in technology, microelectronics, and cyber. Cybersecurity maybe wasn’t a factor when these systems were designed in the 1960s and 1970s, so it’s an important part of what we’re designing in now. 

IEEE Spectrum:The 2018 review notably called for production of low-yield nuclear weapons and a return to a sea-launched cruise missile capability. What’s the rationale?

Kriete: The whole idea behind these two relatively small modifications to our nuclear arsenal is really about disabusing other countries—but especially Russia—of the notion that they might ever be able to use nuclear weapons in a limited way, on a relatively small scale, and have the United States and NATO [North Atlantic Treaty Organization] forces back down.

We feel that the addition of a low-yield ballistic missile warhead, in small numbers, that goes onboard the submarines, would be exactly what’s needed to close that perceived deterrence gap.

The United States had a nuclear sea-launched cruise missile for decades. The 2010 NPR directed that we sunset the last remaining system. But we found that our allies, who do not have their own nuclear weapons but rely on the U.S. nuclear umbrella, were counting on that weapons system quite a bit. There is still deterrence utility to this system, really in more regional scenarios. Think about North Korea, or maybe Chinese aggression in the South China Sea. That’s why we’re in the early steps of doing studies to restore a sea-launched cruise missile capability.

IEEE Spectrum:Critics fear that by producing low-yield warheads, the United States is reviving the nuclear arms race and raising the risk of a nuclear conflict. How do you respond?

Kriete: Nothing that the United States is doing is stimulating a nuclear arms race. If there has been any kind of nuclear arms race in recent years, it’s been with Russia and China, not with the United States. We’ve continued to life-extend what we have. We’ve remained steady, while Russia has increased [its nuclear arsenal and capabilities], China has increased. North Korea is off and running.

Things like the low-yield warhead and the sea-launched cruise missile are really intended to convince the leadership of other countries that they should never even get to the point where they think that they can derive some sort of benefit out of their first use of nuclear weapons. That’s the goal.

IEEE Spectrum: The U.S. National Nuclear Security Administration (NNSA) is working to resume production of plutonium cores, or pits, for nuclear weapons at Los Alamos National Laboratory in New Mexico. Why is this necessary?

Kriete: Plutonium pit production is a great example of how we’ve allowed the nuclear weapons enterprise to decay over the last 10 or 15 years. We haven’t built new plutonium pits in many, many years. We haven’t fielded a new warhead since 1988. But it’s not just about building new warheads. It’s about sustaining the stockpiles of warheads that we have today.

The top-line requirement is that we need to get to a production rate of 80 pits per year by 2030. We have an interim step of getting to 30 pits per year by 2026. As long as we can reach that, we feel confident that we’ll have enough new plutonium pits coming into the stockpile to sustain what we have for many decades into the future.

"Plutonium pit production is a great example of how we've allowed the nuclear weapons enterprise to decay over the last 10 or 15 years."

Los Alamos is the only place currently where we are able to work with plutonium pits, and there’s not a production capability there right now. They do research, development, sustainment, materials analysis—those types of things—to assure that pits that are in service today are still safe, secure, and reliable. The first goal for the NNSA is to grow that [production] capability there, to where we can produce a certain number of pits, and provide them to the Department of Defense to put them in the field when they’re needed.

IEEE Spectrum: The United States and Russia have voluntarily adhered to a moratorium on nuclear weapons testing since the early 1990s. Instead, the United States has used high-energy physics experiments and computer simulations to verify the safety and reliability of its arsenal. Is this Stockpile Stewardship program still sufficient?

Kriete: We’re committed to continuing not to do nuclear explosive testing, so long as we can certify the readiness of the stockpile using other methods. To date, all these other methods have been effective.

Supercomputing is a growing field that’s used to do simulations, modeling, and detailed analysis of the condition of the warheads as they age. All the special nuclear materials that go into a warhead, in addition to the plutonium, uranium—understanding how they age over decades is not very clear sometimes. So it’s a combination of analysis, supercomputing to model what the effects of aging would be, but then also a robust surveillance program.

The national laboratories will periodically take a warhead that might be deployed on a submarine, bring it back, disassemble it, do detailed inspections to see if the warheads actually aged (through corrosion, modification of the shape of the components, etc.) in the way they were predicted to age. And all that gets rolled into the calculations that the brilliant physicists do to certify that the stockpile is safe, secure, and effective.

IEEE Spectrum:What other challenges does the United States face in modernizing the nuclear weapons enterprise?

Kriete: The number of folks working in these areas today, who are highly skilled and very specialized, are retiring faster than we can get new folks in the door. We really need high-end, technical talent to come help advance some of these assignments. We need folks who are mechanical, electrical, and aeronautical engineers, scientists—all kinds of folks.

I toured the Kansas City Plant in Missouri where we build all the non-nuclear components for the weapons—things like supporting electronics that have to be very densely packed into a relatively small area to fit within a warhead. That’s really high-end stuff. The idea of radiation-hardened microelectronics is not something many other industries work on. At the plant, they were pairing workers who had been there for decades with entry-level people, in a kind of mentor-protégé role. They would rotate around, so that the younger folks had an opportunity to learn as much as they could from the limited number of people who have done this stuff for years. I thought this was pretty powerful.

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