President Joe Biden and some congressional Democrats have expressed support for establishing a nuclear declaratory policy of no first use (NFU) or “sole purpose.” Under an NFU policy, the United States pledges never to use nuclear weapons first in a conflict. This functionally means the same as declaring that the sole purpose of nuclear weapons is to deter or retaliate only against nuclear attack—precluding the possibility of using nuclear weapons in response to chemical, biological, cyber, or conventional attacks, regardless of their magnitude.REF

U.S. nuclear declaratory policy has consistently been one of calculated ambiguity, stating that the United States would only use nuclear weapons in “extreme circumstances,” including “significant non-nuclear strategic attacks.”REF Not only have compelling arguments for adopting an NFU policy not been made, but NFU would carry real risk, including eroding deterrence against adversary aggression as well as allies’ confidence in extended deterrence commitments.

Moreover, while the United States faces advancing threats and increasing challenges to its nonproliferation objectives, there is no evidence that current U.S. declaratory policy is driving these trends, nor that changing policy would have a moderating effect. For these reasons, the Obama Administration, Congress, senior military leaders, and U.S. allies have all opposed an NFU policy.REF The Biden Administration should similarly reject calls to adopt an NFU policy and continue the long-standing declaratory nuclear policy of calculated ambiguity.

Why It’s Dangerous

The U.S. should reject the self-limitation of an NFU or sole-purpose policy because it:

Erodes Deterrence Against Adversary Aggression. An NFU policy would assure adversaries they are at no risk of nuclear attack if they launched a chemical, biological, cyber, or conventional attack against the United States no matter how devastating. The more certainty that adversaries have about U.S. plans to use nuclear force, the easier they can plan their aggression to remain below the nuclear threshold. Adversaries could become emboldened to use conventional forces against early warning or nuclear command-and-control assets as preparation for a nuclear strike. China might become emboldened in its quest to overtake Taiwan if a nuclear response is off the table. Proponents argue that NFU would decrease the risk of a war escalating to the nuclear level, but the United States should aim to deter fighting completely. Nuclear forces—meaning the real possibility that they could be employed—deter war more effectively than conventional forces, especially as the United States loses conventional superiority in some domains.REF For example, during the Cold War, the United States used the threat of nuclear force to deter a conventional attack on NATO, convincing Moscow that such an attack could trigger nuclear war.REF

Ultimately, NFU erodes deterrence because it gives adversaries one less response to consider—and to fear—as they weigh the benefits and costs of taking aggressive actions. As former Chairman of the Joint Chiefs of Staff General Joseph Dunford summarized, the “current policy [of calculated ambiguity] is one that complicates an adversary’s decisionmaking process, and I wouldn’t recommend any change to simplify an adversary’s decisionmaking calculus.”REF The President should have all tools at his disposal to deter and respond to attacks that have the potential to inflict major damage against U.S. populations and critical strategic assets.

Erodes Allies’ Confidence in U.S. Extended Deterrence Commitments. An NFU policy effectively communicates to U.S. treaty allies that the United States will not use nuclear force in their defense no matter how deadly a conventional attack or one using weapons of mass destruction. Allies have repeatedly agreed not to acquire their own nuclear weapons because they can rely on the United States to defend them from existential threats. NFU could lead to nuclear weapons proliferation if allies doubt U.S. security guarantees, an outcome that would degrade the United States’ long-standing commitment to nonproliferation.REF For these reasons, allies have opposed an NFU policy in the past.REF Sole-purpose proponents argue that nuclear deterrence is no longer credible against conventional attacksREF—but if correct, the solution is to modernize the U.S. nuclear deterrent, not to undo the promise of the U.S. nuclear umbrella.REF

Will Not Influence Adversaries. Russia declares that it reserves the right to use nuclear force in response to non-nuclear attacks, and recent doctrine indicates a greater willingness to use tactical nuclear weapons first on the battlefield.REF China’s NFU policy is too ambiguous to take seriously.REF As long-time senior defense official Frank Miller described, to think that adversaries will mimic a U.S. NFU declaration “suggests a strong degree of cultural arrogance.”REF The United States has maintained a restrained nuclear posture for the past few decades, yet Russia and China have been building new nuclear weapons. Proponents have provided no evidence that NFU or sole purpose would reverse this behavior.

What Key U.S. Senior Leaders Say

Recent commanders of U.S. Strategic Command (STRATCOM), including General Robert Kehler,REF General John Hyten, and Admiral Charles Richard, have consistently opposed adopting an NFU policy. Last year, Admiral Richard stated, “My best military advice would be to not adopt a ‘no first use’ policy…. [It] would have a significant negative effect on our commitment to our allies.”REF

When he was STRATCOM Commander, General Hyten explained that “anything that simplifies an enemy’s decision-making calculus would be a mistake and that’s exactly what [no first use] would do. That would create an environment where an adversary could think that crossing the line would be okay and that the United States would not respond to whatever the situation was.”REF

President Barack Obama’s former Cabinet officials, Secretaries Ash Carter, John Kerry, and Ernie Moniz, all reportedly opposed adopting an NFU policy due to concern from allies.REF As Carter explained, “It has been the policy of the United States for a long time to extend its nuclear umbrella to friends and allies and thereby contribute to the deterrence of conflict and the deterrence of war and many of our friends and allies have benefited from that over time.”REF

In a spring 2020 Foreign Affairs article, then-candidate Joe Biden expressed his support for sole purpose, and said that he would “work to put that belief into practice, in consultation with the U.S. military and U.S. allies.”REF If President Biden follows through on his commitment to consult with the military and allies, then clearly, he should reach the same conclusion as they did, and as previous Presidents have, to oppose an NFU or sole-purpose policy.

Recommendations for the U.S.

The Biden Administration should:

• Not adopt a no-first-use or sole-purpose declaratory policy for nuclear weapons. The Administration should continue the long-standing policy of calculated ambiguity.

Congress should:

• Reject any efforts to legislate a no-first-use or sole-purpose policy. Congress should remain focused on nuclear modernization.

Patty-Jane Geller is Policy Analyst for Nuclear Deterrence and Missile Defense in the Center for National Defense, of the Kathryn and Shelby Cullom Davis Institute for National Security and Foreign Policy, at The Heritage Foundation. “Dangerous Nuclear Policy Ideas” is a series of Issue Briefs on existing nuclear policy proposals that would, in fact, weaken America’s national security.