In the event of a rapidly escalating conflict with the Russians, should the United States conduct a “limited” nuclear strike to coerce the enemy to back down? Or, in Cold War nukespeak, should the United States “escalate to deescalate” the situation?

Believe it or not, that is a real question that is being debated in the Pentagon today. And the answer is no. Thinking we can use nuclear weapons in a “limited” way without inviting nuclear catastrophe is a dangerous fantasy.

Here is the hypothetical scenario. Russia decides to annex part, or all of, NATO ally Latvia, much like it did with the Crimean Peninsula. Russian forces cross the border, and NATO is forced to respond with a mixed force of U.S. Army brigades, U.S. Marines, air wings, special forces and allied personnel.

All of the sudden, a full-fledged war is threatening to engulf Northern Europe.

Fearing that the fighting will spill over into the rest of Europe, or even break out in Poland or the Ukraine, the United States launches a “tactical” nuclear strike against Russian forces on the border of Latvia.

The hope is that this will cause Russian commanders to pause amidst the destruction, and take a second to reconsider their options now that nuclear force has been used.

In theory, that pause would be enough time for cooler heads to prevail — and for the State Department to cable the Kremlin and hammer out some kind of ceasefire.

To Pentagon planners, this scenario is a legitimate one.

The Air Force already has plans to field a new, low-yield, air-launched nuclear cruise missile that it refers to as the Long Range Standoff Weapon, which critics argue is tailored for limited nuclear war fighting.

“Beyond deterrence, an LRSO-armed bomber force provides the president with uniquely flexible options in an extreme crisis, particularly the ability to signal intent and control escalation,” Frank Kendall, the Pentagon’s top weapons-buyer, told Congress.

But once we’ve opened Pandora’s Box, is it possible to close it again? With thousands of Russian soldiers dead or dying on the Latvian border, would the Russians really just stand down?

Would the United States?

There’s no way to know for sure. But the little data that exists suggests no.

Proud Prophet:

At the height of the Cold War, the Reagan administration worried about the effectiveness of the U.S. nuclear war plan. In fact when he was first briefed on the U.S. strike plan, Reagan became physically ill and the briefing had to be postponed.

In 1983, amidst heightened tensions with the Soviets, the administration put the U.S. war-plan to the test in a war game called Proud Prophet.

According to author and Defense Department advisor Paul Bracken, it was unlike any other war game in Cold War history. Whereas most other war games cast staffers from think tanks, former administration officials and pentagon employees in the roles of U.S. president or Soviet commanders, Proud Prophet involved actual U.S. national-security decision-makers, including Secretary of Defense Caspar Weinberger and the chairman of the joint chiefs.

Furthermore, “to make it as realistic as possible, actual top-secret U.S. war plans were incorporated into the game … [making it] the most realistic exercise involving nuclear weapons ever played by the U.S. government during the Cold War,” Bracken wrote.

The simulation played out around the clock for two weeks, with “hundreds of military officers participating in Washington as well as communicating over top-secret links with all the major U.S. military commands around the world.”

The result? “Many of the strategic concepts proposed to deal with the Soviet Union were revealed to be either irresponsible or totally incompatible with current U.S. capabilities and immediately thrown out.”

Chief among them were the use of limited de-escalatory nuclear strikes. Like in our hypothetical scenario above, “the idea behind these was that once the Soviet leaders saw that the West would go nuclear they would come to their senses and accept a ceasefire … they were supposed to limit a nuclear war.”

But that isn’t how it played out.

“The Soviet Union team interpreted the nuclear strikes as an attack on their nation, their way of life and their honor,” Bracken wrote. “So they responded with an enormous nuclear salvo at the United States.

“The United States retaliated in kind. The result was a catastrophe that made all the wars of the past five hundred years pale in comparison. A half-billion human beings were killed in the initial exchanges and at least that many more would have died from radiation and starvation. NATO was gone. So was a good part of Europe, the United States and the Soviet Union. Major parts of the Northern Hemisphere would be uninhabitable for decades.”

Unfortunately, we have forgotten these lessons.

Misguided U.S. Budget Priorities:

The United States has embarked on an extensive plan to replace, and enhance the lethality of, its nuclear arsenal over the next 30 years. The new nuclear cruise missile alone is projected to cost at least $30 billion, and it was designed for the exact type of scenario that Proud Prophet taught Reagan we must avoid at all costs.

After being briefed on the operational need for the new nuclear cruise missile, Sen. Dianne Feinstein, a California Democrat, told her colleagues in Congress that “the so-called improvements to this weapon seemed to be designed, candidly, to make it more usable, to help us fight and win a limited nuclear war. I find this a shocking concept.”

The notion that nuclear weapons can be used for anything “beyond deterrence” is reckless and dangerous thinking. It is an option that should be taken off the table entirely. Reagan recognized as much after witnessing the disastrous results of Proud Prophet.

“A nuclear war cannot be won and must never be fought,” Reagan said in his subsequent state-of-the-union address.

Even contemporary American officials recognize as much, albeit indirectly. At a hearing where he criticized the Russian doctrine of “escalate to de-escalate,” Deputy Secretary of Defense Robert Work noted that “anyone who thinks they can control escalation through the use of nuclear weapons is literally playing with fire. Escalation is escalation, and nuclear use would be the ultimate escalation.”

Yet that is precisely the capability that American defense planners are seeking to enhance with the new air-launched nuclear cruise missile.

Avoiding Armageddon:

Proud Prophet clearly demonstrated that escalation control is a dangerous theory that must never be tested. As Bracken pointed out, “[Proud Prophet] went nuclear big time, not because Secretary Weinberger and the chairman of the Joint Chiefs were crazy but because they faithfully implemented the prevailing U.S. strategy, a strategy that few had seriously thought about outside of the confines of a tight little circle of specialists.”

That is, in part, why eight senators penned a letter to Pres. Barack Obama arguing that nuclear air-launched cruise missiles are “outdated and unnecessary nuclear weapons [and] relics of the past.”

The letter, organized by Sen. Ed Markey, a Massachusetts Democrat, called for the LRSO to be cancelled and urged the president to “focus on capabilities that keep our economy and defense strong while reducing the role of nuclear weapons.”

Any decision to deploy nuclear weapons will be out of our hands. But we can ensure that inherently destabilizing weapons such as the LRSO are not on the table. We should cut this program.

As Sen. Ted Kennedy argued on the Senate floor in 2003, “a mini-nuke is still a nuke … If we build it, we will use it … it is a one-way street that can lead only to nuclear war.”

The belief that we can control a nuclear exchange is unrealistic. To tell the president that we can put the brakes on a conventional war by using a nuclear weapon is to make a promise that no-one can keep. We have fought plenty of wars in the 71 years since we dropped the atom bomb on Hiroshima. None of them have required the use of a nuclear weapon.

It just takes one nuclear weapon to start Armageddon. We maintain an arsenal of nearly 7,000. Let’s make sure we avoid building the more “usable” ones.

Geoff Wilson is a Research Associate at Ploughshares Fund, a global security foundation that has supported War Is Boring (where this first appeared) in the past.

Will Saetren is the author of Ghosts of the Cold War: Rethinking the Need for a New Cruise Missile, and an alumnus of the Roger L. Hale Fellowship at Ploughshares Fund.