Critical Steps in Biden’s Nuclear Posture Review

By Christine Parthemore

President Biden’s Nuclear Posture Review (NPR) will be released soon. When it is, it will make several policy changes that should greatly benefit U.S. security and international leadership.

One is that the NPR will reportedly declare that the fundamental purpose of nuclear weapons is to deter nuclear attacks.

I and several colleagues at the Council on Strategic Risks have advocated that President Biden adopt a sole purpose doctrine, which would show restraint and reassure the world that U.S. nuclear weapons are only for deterring nuclear weapons use, and retaliating against nuclear attacks if necessary. While the NPR will still hold that the United States views nuclear weapons as potentially needed to deter and respond to significant, non-nuclear strategic threats, this is still a major step in reducing the risks of nuclear weapons use.

This is critical given that the Trump administration’s NPR broadened the perceived utility of nuclear weapons, including by describing them as useful for both deterrence and as a “hedge” against other strategic biological, chemical, cyber, and conventional weapons threats. This was a dangerous expansion of the roles of nuclear weapons that specifically widened the space for using “low-yield” or tactical nuclear weapons for numerous purposes, which can heighten risks of miscalculation and escalation in conflict.

The Biden Administration introducing the concept of fundamental purpose, while not quite as strong as sole purpose, returns to limiting the role of nuclear weapons. In addition to the clear risk reduction benefit, this should strengthen deterrence. The more expansive range of purposes of nuclear weapons was likely not credible to their intended audiences. Clearly nations such as Russia felt free to use chemical weapons without significant fear of U.S. nuclear retaliation, and that lack of deterrence against Russia is now playing out with the looming threat of its use of chemical or biological weapons in Ukraine. Sharpening the focus of U.S. nuclear doctrine should help restore their deterrent effects.

Moreover, a shift to fundamental purpose, a more limited role of nuclear weapons, should help fuel momentum for the United States to increase investment in addressing biological and chemical weapons threats in ways that should be more effective and broadly beneficial. The Department of Defense increased its newest budget request for the Chemical and Biological Defense Program, for example. Such increases should continue in order to expand capacities for deterring and mitigating biological and chemical weapons risks in ways that are both stronger and more credible than the threat of the United States using nuclear weapons in retaliation for biological or chemical weapons use.    

A second—and perhaps even more important—change is that the Biden NPR seeks to end the nuclear sea-launched cruise missile plans for the United States. The revival of this type of nuclear weapon, after multiple past presidents from George H.W. Bush to Barack Obama had eliminated them from the U.S. arsenal, raised significant risks. President Biden’s decision to return to the historical decisions of multiple, bipartisan predecessors will now carry multiple benefits to U.S. security and international stability.

The importance of this decision extends beyond just canceling any single nuclear weapon system. It gives the United States and NATO greater credibility in the future if we aim to convince Russia to abandon these destabilizing weapons, and in aiming to convince others, such as China, not to develop them. The logic of how avoiding these types of nuclear weapons contributes to strategic stability could also show applicability to other nuclear-armed cruise missile systems (i.e., air and ground launched), which could pave the way toward future arms control steps such as a nuclear-only Intermediate-Range Nuclear Forces Treaty follow-on.

Perhaps most importantly, it reduces entanglement and ambiguity between nuclear and conventional weapons systems, which could significantly reduce the odds of miscalculation leading to nuclear conflict.

The United States maintains conventional sea-launched cruise missiles, has used them regularly against countries such as Libya and Syria, and is moving to sell them to Australia as part of the recently-announced AUKUS deal. The United States not possessing nuclear variants of these weapons is the single best option for ensuring that a conventional sea-launched cruise missile strike—for example, in a future conflict involving China or Russia—is not mistaken for a nuclear attack. 

For that matter, ending plans to bring back U.S. sea-launched cruise missiles cuts a potential roadblock in the AUKUS deal and ends a possiblehindrance to potential future U.S. efforts in the Indo-Pacific. Selling conventional Tomahawk cruise missiles to Australia would have been fraught, and even more strongly challenged by China, if the United States possessed nuclear variants. Moreover, much of the region is within the Southeast Asia Nuclear Weapon-Free Zone, which would complicate operations of any U.S. vessel carrying them.  

Last but certainly not least, this decision holds clear, positive logic linking U.S. modernization plans to goals for using arms control as a key part of U.S. national security strategy. Sea-launched cruise missiles are among the trickier weapons systems to verify as nuclear or non-nuclear, and most verification options would likely be seen as intrusive. Keeping these weapons conventional-only—starting now—is drastically easier from a verification perspective than developing nuclear sea-launched cruise missiles and then having to prove later that we have relinquished them.

When the Biden Nuclear Posture Review is released, it will likely be attacked for both not changing enough from past policy and for changing too much. Yet it is already clear that some of the specific decisions made will be incredibly meaningful, and can help us step away from the policies and plans that have put the world at a higher risk of nuclear weapons use than most of us have ever experienced.


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