Though Secretary of State John Kerry is still on a foreign-policy high after recently reaching an interim agreement with Iran that is designed to temporarily halt Tehran’s nuclear program, the Obama administration may do well to contemplate the worst-case scenario should nuclear diplomacy ultimately fail. Such a scenario would likely see Saudi Arabia follow through with veiled threats to acquire nuclear weapons from Pakistan at the first hint of a nuclear capable Iran. It would also see Israel turn its stealth nuclear arsenal into a very active deterrent force. Faint threats to go nuclear have also been heard from Egypt and Turkey—all as tensions continue to rise between China, Japan and the Republic of Korea.

At the same time as Middle East instability is threatening to add four to six additional nuclear powers, nuclear abolitionists are encouraging the president to reduce the U.S. nuclear arsenal well below the 1,550 strategically deployed warheads agreed upon in the New START treaty. What too many in the antinuke crowd don’t seem to understand is that less is not just less, less is different.

For some strange reason, today’s debate over the utility of nuclear weapons is focused on the number of strategically deployed weapons. Discussions surrounding how many is too many and how many is enough are often based on gross assumptions that are made to fit the agenda of the individuals speculating about necessary numbers. To be frank, this approach is shallow and the numbers bandied about are often fraudulent.

Consider the recent report from Global Zero that called for an “illustrative” stockpile of nine hundred warheads. It may seem a reasonable number to some, but it obscures that only 450 warheads would be deployed and zero would be available to the president in a crisis or for generating deterrence day-to-day. The Cato Institute also jumped on the bandwagon, recommending elimination of the intercontinental-ballistic-missile force to ensure funding for nuclear-armed submarines. Such a force structure and posture would leave the nation vulnerable to blackmail by adversaries retaining substantial, responsive nuclear weapons. It would also make it impossible for the United States to credibly stem the tide of nuclear proliferation in the Middle East by offering a credible nuclear umbrella to states like Saudi Arabia—and credibility is key.

Rather than taking a “less is better” approach, as the abolitionist movement does, numbers should flow from strategy. The debate should center on which nuclear capabilities remain critical to our security. It is high time the United States abandon the search for “Goldilocks” solutions.

Today’s debate is rooted in name calling. Disarmament advocates accuse deterrence practitioners of Cold War thinking, a straw man intended to deflect attention to sound analysis through disparagement. The landscape has radically changed since the Cold War and will continue to change as the US attempts to play a leading role in prevent nuclear proliferation in the Middle East and elsewhere. No one understands this better than today’s practitioners. The condition of Mutually Assured Destruction (MAD) is on the brink of extinction. If MAD was ever a satisfactory proxy for stability, it is no longer.

Today’s debate needs to move on to how things have changed. A concept that has gained attention in the physical sciences over the past several decades is that “More is not just more, more is different.” If more is different, it follows that less is different and we should expect surprise on the path to lower numbers. The United States has come to rely on the nuclear triad to produce specific attributes such as survivability and responsiveness. If the country continues down the path to zero, there will be thresholds where the ability to provide deterrence attributes will unexpectedly change. While abolitionists view arsenals declining in a linear fashion, they seem to forget that the importance of each warhead and weapons systems as well as the complexity of the deterrence environment, does not change linearly. In fact, not only does the physical ability to guarantee deterrence become increasingly problematic, but American credibility will vanish, promoting the very proliferation abolitionists oppose.

Today’s debate should build consensus. Increasing stability and strengthening deterrence through better understanding of modern dynamics presents the best opportunity to “right size” the arsenal. The American military left Cold War thinking behind long ago and understands nuclear deterrence in the twenty-first century. Retaliatory forces remain necessary, but in a strategic environment with lower numbers, continued reductions may result in a mix of nuclear capabilities inadequate to guarantee deterrence. Extended deterrence—in Europe, Asia, and potentially the Middle East—is no longer a sub-component of MAD and requires its own capabilities and strategies. The role of missile defense in guaranteeing the credibility of extended deterrence is clarifying itself as ballistic missile threats to American allies in Europe, Asia, and the Middle East grow. As recent events in East Asia demonstrate, nuclear-capable bombers continue to prove their importance as tangible reminders of American security commitments.

Rather than making idealistic statements, today’s nuclear-weapons debate must acknowledge that less is different. The United States and Russia have decades of experience in nuclear deterrence, but in a post-Cold War world the Russo-American relationship is only a small part of the deterrence framework. That experience was earned in a bipolar relationship in which both actors had many thousands of nuclear weapons and delivery systems. Although that relationship still exists, significant reductions in the size of both arsenals have altered the relationship in ways not yet apparent to either actor.

Contrary to the accusations of nuclear abolitionists who suggest that nuclear maximalists are stuck in the Cold War, it is they who seem to forget that the world in which the nuclear superpowers earned their experience no longer exists. The fact is that experience is only partly applicable to our current and future needs. If this reality remains unrecognized, overconfidence in our ability to predict and influence our nuclear peer and others could lead to instability and deterrence failure, especially in a crisis situation.

In pursuit of stability, the ability to rapidly respond will be critical. This speaks to the need for flexible and nonfragile strategies, force structures and force postures. At a minimum we should put a premium on flexibility and diversity by retaining redundancy in communications architecture and weapons-delivery systems and avoiding fragility in all such structures and systems.

America stands on the precipice of an unprecedented nuclear world. Nuclear deterrence at 1,550 warheads today is not an inverse of 1952, when the United States broke through 1,550 on the way to 34,000. At that point, the USSR had approximately one hundred warheads and was the only other country to have nuclear weapons. That deterrence environment was neither complex nor large. Today and well into the future we face an environment of multiple nuclear-armed peers, near-peers, and regional actors that could pose a threat to the United States and its allies. A dramatic increase in the number of nuclear powers would prove a time of instability and require a capable American arsenal to deter the use of nuclear weapons by any state in the Middle East.

The reality facing the United States is such that nuclear deterrence remains vital to our collective security. As nuclear abolitionists press for further reductions in the American nuclear arsenal, they would be well advised to remember that less is not just less, less is different.

Dr. A. B. Lowther is a non-resident Senior Fellow at the Center for the National Interest and Hunter Hustus is a PhD candidate at Northeastern University. Their most collaboration is Deterrence: Rising Powers, Rogue Regimes, and Terrorism in the Twenty-First Century (Palgrave-McMillian).

Image: Flickr/chb1848. CC BY-SA 2.0.