One of the things President Obama could still do before leaving office is to cut the “hedge” force. These are nuclear weapons that the United States keeps in reserve for two reasons: technical and geopolitical. The argument for the technical hedge is that, if deployed weapons of one type experienced a problem, the U.S. could instead deploy weapons of another type from the hedge force. The geopolitical argument is that the international security situation could change, leading the United States to want to increase the number of deployed weapons.
In reality, both of these scenarios are extremely unlikely. The current nuclear stockpile is thoroughly understood and can be well maintained for decades to come by taking a sensible approach and minimizing warhead changes. It is also hard to imagine such a sudden change in the geopolitical situation that the United States would want to quickly deploy more nuclear forces. UCS and many others have long argued that the United States could reduce its arsenal to 1,000 warheads total, including hedge forces, and have more than enough warheads to ensure our security under any circumstance.
But setting that all that aside, let’s look at the current numbers in the hedge and how they could be reduced. The US keeps about 2,750 weapons (2,400 strategic and 350 tactical) in the hedge.
To comply with the New START treaty, the United States and Russia will each reduce their deployed accountable strategic weapons to 1,550 by 2018. For the United States, the actual number will likely be roughly 1,750. (This number is larger because of the way the treaty defines what counts as a weapon—bombers count as only one weapon even though they may carry multiple bombs or air-launched cruise missiles.) A study by my colleague Lisbeth Gronlund shows that the current U.S. hedge of 2,400 strategic warheads is almost twice the required technical hedge for an arsenal of that size with existing warhead types. Cutting the hedge would eliminate the costs of maintaining and storing these weapons, as well as reduce the overall U.S. arsenal and be a step toward eliminating nuclear weapons, as the United States is obligated to do under the terms of the Nuclear Non-Proliferation Treaty. President Obama could use his authority to order an immediate reduction in the size of the hedge, thereby transferring these weapons to the dismantlement queue.
Immediately Cut the Existing Hedge
A 2013 administration report to Congress states that the Departments of Defense and Energy have re-examined their approach to determining the size of the hedge needed and concluded that a new, more efficient, strategy would allow the United States to “maintain a robust hedge against technical or geopolitical risk with fewer nuclear weapons.” It goes on to say:
A non-deployed hedge that is sized and ready to address these technical risks will also provide the United States the capability to upload additional weapons in response to geopolitical developments that alter our assessment of U.S. deployed force requirements.
In other words, a hedge that is large enough for one scenario (the failure of all weapons of one type) is also large enough to cover another scenario (a U.S. desire to quickly deploy more weapons for political reasons). That is actually significant progress, though it hasn’t led to any changes in the hedge yet.
Looking further ahead, the FY 2016 Stockpile Stewardship and Management Plan, which details plans for maintaining and upgrading U.S. nuclear warheads, states that the United States could eventually reduce the hedge by up to 50 percent. However, it specifies that this is only possible once the United States fully implements its ambitious “3+2” plan to replace its four types of ballistic missile warheads (two on land-based intercontinental ballistic missiles and two on submarine-launched ballistic missiles) with two sets of three newly-designed “interoperable” warheads—one set for use on ICBMs and the other on SLBMs. While the warheads themselves would not be interoperable (the ones for ICBMs would differ from those for SLBMs), the core of the weapon—the so-called nuclear explosive package—would be. Fully implementing the 3+2 plan will take decades, however, so this is irrelevant to current consideration of the hedge.
The same DOD document that talks about re-examining hedge requirements also discusses using “intra-leg hedging” to replace a failed weapon—in other words, replacing a failed SLBM warhead with another SLBM warhead, or a failed ICBM warhead with another ICBM warhead. Currently, it is not possible to do this with SLBM warhead types because while the arsenal includes two warheads for subs—the W76 and the W88—nearly all of the W88s are deployed, so none would be available as a backup if there were a problem with the W76. Instead, the United States would have to compensate for a problem with the W76 by deploying additional land- and air-based weapons, a strategy known as “inter-leg hedging.” While this would result in the same overall number of deployed weapons, fewer would be submarine-based. This has been the case with the U.S. arsenal for decades, and has not caused any problems. However, some DOD planners now see a chance to move toward their ideal “intra-leg” hedge force, and want to take it via the 3+2 program.
But there are a number of problems with building new warhead types to replace those in the existing arsenal. First, there are technical concerns. Using a nuclear explosive package that has not previously undergone nuclear explosive testing may reduce confidence in the reliability of the new warhead. This could lead some political and military leaders to push for renewed “proof testing” to demonstrate that the newly modified warheads will work as intended.
The unclassified executive summary of a study of the 3+2 plan by JASON, an independent group of scientists that advises the government, expresses skepticism about its benefits based partly on technical issues, noting that some of the program’s goals may compete with each other, and that some of the changes under consideration could “alter reliability or targeting accuracy.”
Second, on the political side, building new warheads could undermine U.S. nonproliferation goals by calling into question the U.S. commitment to the Comprehensive Test Ban Treaty and the Nuclear Nonproliferation Treaty. Finally, the 3+2 approach is almost certain to be more expensive than maintaining the existing stockpile through straightforward life extension programs. For example, the cost of the life extension program for the W76 warhead—the most common warhead in the U.S. stockpile—is around $4 billion. The cost estimate for the first warhead in the 3+2 plan is roughly twice that, and for far fewer warheads.
Moreover, as mentioned above, completing the 3+2 plan would take at least three decades. In short, the 3+2 plan is not the way to cut the hedge.
The good news is that the UCS study mentioned above finds that, for a New START-sized arsenal with existing warhead types, the hedge only needs to include 1,250 weapons to provide replacements in case of the technical failure of an entire class of weapon. And, as noted above, the DOD already concluded that there is no need for additional warheads beyond the technical hedge to meet its requirements.
In other words, rather than waiting decades to complete the 3+2 plan, the president could announce that the United States will immediately reduce the strategic hedge by 1,150 weapons—leaving 1,250.
In addition to strategic weapons, the hedge also contains 350 tactical weapons, all of which could be eliminated. These weapons are all B61 bombs, and would allow the US to add to the 180 tactical B61 bombs it currently deploys in Europe, or to deploy them elsewhere for “extended deterrence” purposes. The existing B61 bombs come in four versions, but are all in the process of being replaced with a single new variant—the B61-12—which will also serve as the U.S. strategic bomb. (The other existing U.S. strategic bomb, the B83, is planned for retirement.) Since there will no longer be a distinction between tactical and strategic bombs, there will no longer be a need for a separate tactical hedge.
Re-examine the Need for a Technical Hedge
More fundamentally, while immediately moving to cut the existing hedge, the United States should also reconsider the logic behind its decision to retain a technical hedge in the first place. Both Britain and France have significantly smaller and less diversified arsenals than the United States. Neither maintains a hedge in case of technical failures of their nuclear weapons. They also do not maintain multiple types of warheads for each delivery system. (France deploys one warhead type on submarines and another on aircraft. The UK deploys only one warhead type, on submarines.)
The failure of an entire class of weapons is highly unlikely, at least for existing weapon types, which have undergone nuclear explosive testing. The president should order a study to quantify the odds of such a failure and investigate whether it is necessary to maintain a technical hedge at all. Even if such a study finds that a technical hedge is advisable, it should not be necessary to employ three separate hedging strategies: keeping a technical hedge, deploying two types of warheads per delivery system, and deploying two types of ballistic missile delivery systems.
We updated the numbers on 12/15/16 to reflect new estimates by Hans Kristensen.