In the early part of 2020, the USS Tennessee ballistic missile submarine quietly set out to sea in the Atlantic Ocean on a historic deterrent patrol. In the past, this submarine could launch ballistic missiles armed with the W76-1 warhead (a 90 kiloton yield) or the W88 warhead (a 455 kiloton yield). Now the Ohio-class submarines carry at least one W76-2 warhead with a yield of about five to eight kilotons.

The low-yield nuclear warhead allegedly provides the U.S. with a needed capability for deterring the potential use of tactical nuclear weapons by Russia, a prospect considered more likely under its current nuclear doctrine. Proponents claim these new weapons are prompt, useable, and capable of circumventing Russia’s air defenses.

U.S. policymakers fear Putin may engage in expansionist behavior in Eastern Europe in which he resorts to using tactical nuclear weapons, severely limiting their plausible response options. To be deterred, the Russians must believe that U.S. policymakers will respond in a way that is costly to their interests. Policymakers say the new capability will raise the threshold of Russia’s potential use of tactical nuclear weapons. For this reason, the new warhead will ensure the credibility of U.S. nuclear deterrence, closing a key capability gap that can be exploited by adversaries.

But these claims beg two questions. Does this new weapon lead to enhanced credibility? If so, at what cost?

Whenever U.S. policymakers express their fears of a “capability gap”, it’s hard not to think of Stanley Kubrick’s 1964 parody of nuclear weapons policies, Dr. Strangelove. While esteemed experts have proposed plenty of valid arguments against deploying low-yield nuclear weapons on submarines, it is also worth considering what the film might teach us about credibility, capability gaps, the practicalities of deterrence theory, and the essential role of perception.

After consulting with Nobel Laureate Thomas Schelling, Kubrick defines deterrence in his film as “the art of producing in the mind of the enemy... the fear to attack."

Schelling suggests the threat of violence implied by deterrence requires explicit or implicit collaboration between a “deterrer” and a “deterree” to achieve the common interest of avoiding mutual destruction. This assumes country leaders are rational, spend time evaluating the costs and benefits of multiple courses of action, and communicate clearly about the nature of their deterrent. The country being deterred will refrain from an action if it proves to be too costly. If one party refuses to collaborate or uphold the assumption of rationality, then deterrence fails.

To determine what might be costly for its adversaries, the U.S. must therefore get into their heads and see the world from their perspective. An adversary must believe that the U.S. has the will and capability to follow through with a particular threat. The deterrent must be credible.

Since nuclear deterrence does not involve the actual “use” of nuclear weapons, but rather the threat of their use, it occurs largely in the minds of the “deterrer” and the “deterree”.

When President John F. Kennedy first took office in 1961, many people perceived the credibility of the U.S. nuclear deterrent to suffer from a so-called “missile gap” vis-a-vis the Soviet Union—a threat which turned out to be in error. The launch of Sputnik in 1957 and Khrushchev’s bluster about the Soviet superiority generated a widely-held impression that the U.S. trailed far behind the Soviets in ballistic missile technology. But the gap was actually in United States’ favor.

To close the gap, the Kennedy administration deployed the “Jupiter” nuclear missiles to Italy and Turkey with the Soviet Union as their intended target. Meanwhile, Khrushchev decided to place intermediate-range missiles in Cuba in an effort to restore the perceived imbalance in capabilities.

Both countries engaged in increasingly provocative behaviors with nuclear weapons to ensure the credibility of deterrence, which ultimately led to the Cuban Missile Crisis and nearly caused an all-out nuclear war. A similar plot plays out in Kubrick’s film, ending in catastrophe.

Dr. Strangelove suggests that a capability gap exists because we think it exists. Alternatively, it exists because we fear our adversary thinks it exists. The gap does not have to exist beyond the human imagination. It is the fear evoked by the perceived capability gap that matters.

Therefore, whatever U.S. policymakers think about the supposed “capability gap” will have real world effects. But these effects will not necessarily benefit U.S. national security in the way they intend. It depends on how their adversaries think about it.

In the film, plans to enhance credibility of a nuclear deterrent go awry, bringing about the very nuclear catastrophe such actions were designed to prevent.

A deranged general activates a Top Secret plan designed to ensure prompt retaliation in the event of a Soviet attack on U.S. leadership by allowing lower-level commanders to give nuclear launch orders. If a first-strike nuclear attack inevitably leads to an all-out nuclear war, it would never be in the Soviet Union’s interest to start one.

As absurd as it seems, creating a situation in which the loss of central command and control of nuclear weapons might occur was perceived as an effective strategy for enhancing credibility during the Cold War.

As absurd as it seems, creating a situation in which the loss of central command and control of nuclear weapons might occur was perceived as an effective strategy for enhancing credibility during the Cold War. By exacerbating the risks and uncertainties inherent in nuclear conflict, adversaries were believed to refrain from taking escalatory actions.

The problem with enhancing credibility of a nuclear deterrent is that such actions rely on the strict rationality of both parties. Even if leaders are rational in the purest sense, they often lack necessary information to properly analyze the costs and benefits for all possible courses of action, which can lead to dangerous miscalculations.

While U.S. policymakers may perceive the new low-yield capability as enhancing credibility, Putin may still be prepared to call the U.S. bluff on the strength of its will to use nuclear weapons of any yield.

As illustrated in Dr. Strangelove, plans grounded in deterrence theory are prone to nuclear catastrophe when put into practice. Decentralizing command and control enhances credibility, but it also introduces a significant risk of unauthorized nuclear war.

During the Cold War, the U.S. deployed thousands of tactical nuclear weapons to Europe to credibly deter an attack from the Soviet Union where it enjoyed significant conventional superiority.

Many tactical nuclear weapons required pre-delegation authority to enhance credibility. For example, the Davy Crockett light recoilless rifle carried a W54 warhead with a yield of 10 to 20 tons. These weapons were mounted on jeeps, operated by a three-man crew, and deployed to the front lines in Europe.

Although the weapon’s lethal radius famously exceeded its range, Carl Kaysen, a prominent nuclear deterrence strategist during the Kennedy administration, expressed greater concern about its implied pre-delegation authority.

Nuclear deterrence makes good sense in theory, and holds up in the minds of deterrer and deterree. As long as nuclear war does not occur, deterrence has succeeded. However, when nuclear deterrence is implemented as a military strategy, it can translate into absurd situations that actually increase the risk of nuclear war.

The conflation of communication with perception was a paramount theme in Dr. Strangelove. In the film, the President goes as far as allowing the Soviet Ambassador into the War Room to clear up any misunderstandings.

But, clear communication does not guarantee accurate perception. This is where the new submarine-launched low-yield nuclear warhead becomes especially problematic. Deploying low-yield nuclear warheads on a strategic delivery system produces dangerous uncertainties if U.S. policymakers attempt to use them. And they have to at least be willing to use them for the sake of credibility.

If they’re used, will the Russians perceive the attack as limited? If asked this question, Dr. Strangelove would likely respond: "The whole point of a limited response... is lost...if your adversary can’t tell the difference!"

If under attack from a ballistic missile submarine, the Russians are likely to assume the worst if they can’t determine the exact yield of the warhead on an incoming SLBM. And the worst would lead to nuclear war with the United States.

In fact, as a result of this risk, U.S. policymakers might be self-deterred and reluctant to use these weapons in the first place. Putin is likely to anticipate this, which would entirely defeat the purpose of the new capability while increasing the potential for nuclear war.

In his film, Kubrick demonstrates the absurdity of a capability gap in a concluding discussion about “doomsday gaps” and “mineshaft gaps”.

The new low yield nuclear warhead deployed on ballistic missile submarines fails to enhance credibility. It also increases the risk of nuclear war. As a result, this new weapon does not make us safer, but rather invites potential misunderstanding with adversaries.

Let’s draw on lessons from history and pop culture and avoid repeating past mistakes.

Natasha Bajema is the Founder and CEO of Nuclear Spin Cycle and the host of the Authors of Mass Destruction Podcast. Follow her on Twitter @WMDgirl.