Key point: Tactical nukes increase the danger of nuclear use. They are small but they still count as weapons of mass destruction.

It was a small, obscure-sounding item in the 2020 defense budget—a mere $19.6 million to procure W76-2 warheads, a sum which could pay for just one quarter of a single F-35A stealth fighter.

But it, along with a select few other items including plans for a Space Force and border wall funding, generated such controversy that Senate Republicans and House Democrats spent three additional months hashing out a compromise defense budget after striking an initial deal this summer.

Ultimately, the House conceded on most of its defense policy priorities—meaning funding will continue flowing to deploy the W76-2 nuclear warheads manufactured by the Pantex plant in Texas.

The W76-2 is a less powerful variant of the W76-1 warhead deployed on 13.5-meter-tall Trident II ballistic missiles deployed on the U.S. Navy’s Ohio-class submarines. Whereas the four 90- or 100-kiloton independently reentering warheads carried on a standard Trident each explode with six times the force of the Little Boy uranium bomb that killed over 60,000 Japanese at Hiroshima, the 5 to 7 kiloton W76-2 has an explosive yield a third or half that of the Hiroshima blast.

The difference reflects that the W76 is a strategic weapon designed to obliterate hardened nuclear missile silos and annihilate large populated areas in an apocalyptic nuclear war—and more pointedly, to deter foes from initiating such a war—while the W76-2 is a tactical nuclear weapon designed to hit individual military bases and formations on the battlefield. 

The W76-2 has been championed by officials such as former Defense Secretary James Mattis as a means to give the U.S. military an additional too with which to retaliate rapidly and proportionally to the tactical nuclear weapons possessed by Russia. 

But opponents, including many former senior defense and foreign policy officials and a broad swathe of arms control experts fear that introducing such a capability simply increases the risk of devastating nuclear war.

Escalate to De-Escalate?

In the 1950s, it was initially assumed that small nuclear weapons would liberally—even routinely—be employed in future battlefields. However, when their use was simulated in NATO’s aptly-named Carte Blanche wargame in 1955, the results were horrifying.

At best, the “small” nukes were used in such large numbers that Europe was left a devastated, irradiated wasteland. Worse, the fighting could cause both sides to escalate to large-scale strategic nukes.

Today, U.S. defense officials fear that Moscow may espouse an “escalate to deescalate” doctrine in which a tactical nuclear strike is employed to signal Moscow’s resolve. Such a limited strike or strikes might be employed after Russian conventional forces have secured a vulnerable target (ie. the Baltics) and before NATO has mustered a large-scale counterattack, in order to convince member states to back down from a conventional conflict Russia would likely lose. 

Unlike strategic nukes, tactical nuclear weapon numbers are not regulated by treaty. Russia has around 2,000 tactical nuclear weapons which can be launched by tube artillery, cruise and ballistic missiles, and air-dropped munitions. 

As Russia’s odds of winning a conventional war against a fully mobilized NATO are slim, the thinking goes that intimidating adversaries into backing down by leveraging the threat of Russia’s nuclear arsenal may be Moscow’s only winning strategy.

Arms control advocates point out Russia’s tactical arsenal actually has shrunk in the last decade, so that claims that the threat is growing are dubious. Furthermore, evidence as to whether Moscow genuinely plans on an “escalate to deescalate” strategy is mixed at best, and contradicted by official doctrine.

However, defense hawks argue that new Russian hypersonic missiles may allow Russia’s nukes to hit their targets faster, and with less chance of being intercepted, than before.

Thus, the Trump administration’s 2018 Nuclear Posture Review argued the United States should expand its tactical nuclear strike capabilities so that it could proportionally retaliate against Russian tactical strikes. As with much nuclear strategy, the ultimate “victory” for such weapon is to deter enemies from necessitating their use in the first place.

However, the United Staes already maintains an arsenal of around 500 air-dropped B61 tactical nuclear bombs with a yield that can be dialed from .3 to 400 kilotons. 150 B61s are forward deployed and shared with select NATO partners. These can be dropped by fourth-generation jet fighters (F-15, F-16 and German Tornados), long-range B-2 stealth bombers and soon F-35 stealth fighters.

Advocates for the W76-2 argue that jets aren’t good enough, as they take longer to deploy and reach their target than ballistic missiles and may suffer losses to Russian air defenses. 

By comparison, a Trident missile can be launched within minutes of receiving a low-frequency signal from an E-6 Mercury “doomsday” plane, can hit a target thousands of miles away within a half hour traveling at up to twenty-four times the speed of sound, and doesn’t put pilots at risk.

However, critics point out that the submarine launching the Trident will be placed at increased risk afterwards as the launch exposes its general position, endangering the submarine’s roughly 150 crew and the vital strategic missiles it carries.

They also argue that difference in response speed shouldn’t matter that much for retaliating against a “signaling strike,” as the intention is less about hitting a specific military target in a short time window than conveying a political message.

But there’s a much scarier risk: Russia likely wouldn’t be able to distinguish a Trident carrying a tactical warhead from a strategic one. And a Trident launched from the Atlantic at a tactical target in Eastern Europe may look very much like it could be headed to wipe out Russia’s leadership in Moscow instead. 

Thus, a tactical Trident strike could inadvertently trigger a strategic nuclear riposte—the kind that could result in some or all the major cities in the United States and/or Europe meeting the same fate as Hiroshima.

In fact, when the United States tested its own “escalate to deescalate” doctrine in the 1983 “Proud Prophet” wargame, it decided to disavow the strategy after discovering it invited precisely such a disastrous consequence.

Weaker, more “useable” nuclear weapons may indeed also be perceived as having a lower threshold for use—particularly by civilian leaders who misjudge the implications—increasing the risk that the chain of escalation described above occurs.

Thus, most arms control experts argue that deploying additional less-destructive nukes actually increases the odds of a civilization-shattering nuclear conflict.

Essentially, whether the W76-2 improves American security is much more about psychology than technology. Would the presence of tactical-yield Trident missiles dissuade U.S. adversaries from employing their own tactical nukes against U.S. forces or their allies? 

And even if that’s the case, would that benefit outweigh the risk that the tactical Trident option makes use of nuclear weapons seemingly more usable and likely, and that such use could inadvertently escalate to a strategic nuclear conflict?

We can only hope such scenarios remain strictly theoretical. With the policy fight resolved in the weapon’s favor in Congress, the new warheads should soon enter service on Ohio-class submarines if they have not already, giving them a new tactical nuclear capability along with their established strategic nuclear mission. 

Sébastien Roblin holds a master’s degree in conflict resolution from Georgetown University and served as a university instructor for the Peace Corps in China. He has also worked in education, editing, and refugee resettlement in France and the United States. He currently writes on security and military history for War Is Boring. This first appeared in 2019.

Image: Reuters