Long before Iraq and Iran, the United States was wrestling with the problem of how to strike North Korea, where planning for the use of nuclear weapons ran into various dead-ends.

The current situation with North Korea is not the first time Americans have wrestled with the problem of nuclear conflict with small states. In 1969, Richard Nixon ordered options for nuclear targets against North Korea, and eventually abandoned his plan for punitive strikes. Little has changed in the nature of the dilemmas facing U.S. planners in North Korea and (should all else fail) Iran. Below is an excerpt from my 2014 book, “No Use,” in which I discussed the Nixon plan and the problem of American nuclear use against smaller powers.

I just don’t think nuclear weapons are usable . . . I’m not saying that we militarily disarm. I’m saying that I have nuclear weapons, and you’re North Korea and you have a nuclear weapon. You can use yours. I can’t use mine. What am I going to use it on? What are nuclear weapons good for? Busting cities. What President of the United States is going to take out Pyongyang?

—General Charles Horner, U.S. Air Force, 1994

The post-Cold War problem of rogue state nuclear proliferation is no longer hypothetical. These small powers, whom Clinton administration national security advisor Anthony Lake in 1994 termed “outlaw” or “backlash” states, not only remain “outside the family of nations,” in Lake’s words, but also “assault its basic values.”

North Korea’s nuclear tests and rash threats represent more than the entry of a new member into the nuclear club. Nuclear weapons are now in the hands of a small, unpredictable state whose foreign policy remains centered on hostility to the United States, whose arsenal is not dedicated to a specific opponent (as in the cases, for example, of India and Pakistan), whose regime remains in a state of declared hostilities with a U.S. ally, and whose leaders remain outside of any constraining alliance system. The North Korean regime has joined the nuclear game with no pretense to being a status-quo power, and no superpower competition to restrict its ambitions.

The North Korean challenge raises issues that go far beyond Pyongyang and Washington. Other states that are no friend to the liberal international order, particularly the terror-supporting theocracy in Iran, are seeking nuclear arms as well. How can small states, crowded by innocent neighbors and commanding only comparatively tiny arsenals, be deterred?

Nuclear Bombs Make Big Explosions

There are severe practical barriers to the use of nuclear weapons against these smaller powers, whether the aggressor is in East Asia, the Middle East or any other area where U.S. leaders will want to limit the impact of conducting what they will hope is a “small” nuclear war. Possible nuclear targets might be too close to a range of objects the United States and its allies may not wish to destroy, including natural or historical treasures. They will certainly be too close to millions of innocent human beings both in the targeted country and nearby.

This is the problem of “co-location,” the nesting of military or nuclear-related assets near civilian areas. Iran’s most important nuclear reactor, for example, is less than ten miles from the city of Bushehr and its 160,000 inhabitants; likewise, the Iranians have placed a uranium enrichment facility some 20 miles outside Qom, one of Iran’s treasured holy cities. North Korea’s Yongbyon nuclear facility is slightly more than 50 miles from Pyongyang, the capital city of more than three million that itself could be a target for retaliation.

Co-location is almost always a problem with strategic attacks, as experiences with the use of aerial bombing from World War II to Vietnam and the Gulf War have repeatedly shown. The dilemmas of targeting in small countries are especially aggravated by co-location issues because of the narrow geography of these states; military, civilian, and infrastructure assets are close to each other because literally everything is close to everything else.

An additional problem is that small nations are situated in crowded neighborhoods, and the effects of a nuclear exchange would be traumatic on nearby states. Not only can rogue regimes hold their own populations as human shields against nuclear attack, but they are also protected by the many innocent people who live near them—or more precisely, by the unwillingness of more civilized nations to kill or injure those innocent populations.

These geographic problems have already frustrated American planners in previous conflicts and crises. As U.S. Air Force General George Butler noted in 1999, “this lesson has been made time and again, in Korea, in Indochina and most recently in the Persian Gulf, [when] successive presidents of both parties have contemplated and then categorically rejected the employment of nuclear weapons even in the face of grave provocation.” Before the 1991 Gulf War, for example, the Americans were intentionally vague about what might happen should the Iraqis use chemical weapons against Allied troops, precisely because U.S. leaders did not want to get boxed in by their own threats.

President George H. W. Bush’s national security advisor, Brent Scowcroft, later recalled a January 1991 White House meeting: “If Iraq resorted to [chemical arms], we would say our reaction would depend on circumstances and that we would hold Iraqi divisional commanders responsible and bring them to justice for war crimes. No one advanced the notion of using nuclear weapons, and the President rejected it even in retaliation for chemical or biological attacks. We deliberately avoided spoken or unspoken threats to use them on the grounds that it is bad practice to threaten something you have no intention of carrying out” (emphasis added).

Too Many Disadvantages against North Korea

Long before Iraq and Iran, however, the United States was already wrestling with the problem of how to strike North Korea, where planning for the use of nuclear weapons repeatedly ran into various dead-ends. Declassified U.S. documents show that in 1969, for example, President Richard Nixon sought plans for dealing with North Korean military provocations, including an April 1969 North Korean attack that resulted in the downing of a U.S. reconnaissance plane. The Pentagon eventually provided Nixon with 25 alternatives, including an operation code-named FREEDOM DROP, the “pre-coordinated options for the selective use of tactical nuclear weapons against North Korea.”

There were three overlapping options in FREEDOM DROP. The first was a “punitive attack against up to 12 military targets with nuclear weapons of a yield of .2 to 10 kilotons.” (By comparison, the bomb dropped on Hiroshima was about 15 kilotons.) The next plan added an attack to neutralize North Korea’s air force (now obsolete, but then a major threat) by striking all 16 major North Korean military airfields with nuclear weapons in the 70-kiloton range. Finally, the third alternative was a broader attack with nuclear weapons ranging from 10 to 70 kilotons “aimed at diminishing greatly North Korea’s offensive capability” and included everything in the first two options plus 22 additional military targets.

In the end, Nixon and his advisors realized that nuclear force held no answers for dealing with Korea. The United States would have had to engage in wide strikes to suppress the North Korean military, which would have caused immense destruction and risked escalation to a wider war in the region.

In 1969, of course, the Cold War situation in East Asia was far more dangerous and complicated than it is today, with America’s Soviet and Chinese adversaries nearby (and already in an undeclared shooting war with each other along their common Asian border), and a much stronger North Korean force facing a weaker U.S. and South Korean defense. Still, U.S. presidents since Nixon have all faced the same problems when thinking about the use of nuclear weapons in North Korea.

The Potential Collateral Damage Is Huge

One option for retaliating against small states might be to engage in infrastructure targeting, in which the regime is destroyed with coordinated nuclear attacks on industry, energy, and other targets besides populations. Again, however, the problem is that small nations do not have significant strategic depth or wide expanses of territory, and there would be almost no way to establish practical differences between bombing only infrastructure and bombing everything else. From the Russian border to the 38th parallel, North Korea is less than 500 miles long, or about the distance from Boston to Washington DC. In places, it is narrower than 200 miles.

North Korea is less than 500 miles long, or about the distance from Boston to Washington DC.

Iran presents a similar problem, if on a slightly larger scale. The entire length of Iran is some 1,500 miles, and in overall territory it is roughly the size of Alaska. This might seem like a fairly vast space, but fewer than 740,000 people live in Alaska, while Iran has a population of 78 million, with more than a fifth of its people concentrated in its five largest cities and most of its military and nuclear facilities in or near those cities.

In the case of North Korea, there is an added problem: the DPRK is an impoverished country with very little infrastructure worth striking, or at least none that would require the use of nuclear weapons. In a tiny state, with an almost nonexistent economic infrastructure and most of its 22 million people already starving, even a small number of nuclear attacks could end up killing, in one way or another, almost the entire population.

American leaders have implied that they know and understand this problem, and that it might even enhance deterrence. The complete destruction of the North may have been what President Bill Clinton was implying in 1993 when he warned that if North Korea ever used a nuclear weapon, not only would the United States “quickly and overwhelmingly retaliate,” but that for the North Koreans it “would mean the end of their country as they know it.”

In 1994, Senator John McCain (later the 2008 Republican presidential nominee) was even clearer when he was asked about North Korean motives and whether Pyongyang’s usual threats were bluffs. “I don’t know,” McCain replied. “But I know what they understand and that is the threat of extinction.”

If You Break It, You Own It

Nuclear attacks on North Korea, Iran, or other small states may not result in complete extinction, but they will effectively destroy them as functioning nations, at which point victory will bring its own complications. The United States and its allies have always in previous wars assumed their proper responsibilities to their defeated enemies, including feeding and caring for the occupied population, reconstruction of the conquered territory, and reintegration of the defeated nation into the international system. (As Secretary of State Colin Powell warned before the 2003 invasion of Iraq, this is the rule that says: “If you break it, you own it.”) The aftermath of a nuclear attack, however, will overwhelm both the immediate palliative and long-term reconstructive capacities of the winner and the loser alike.

The sheer number of burn victims, to take but one example, will represent a disaster beyond any hope of remedy.

The sheer number of burn victims, to take but one example, will represent a disaster beyond any hope of remedy. The specialized facilities needed to treat burn victims are a rare resource across the world: the United States itself has only 2,000 of these so-called “burn beds” in the entire country. A nuclear attack of almost any size, even in relatively under-populated areas, will produce more burn injuries than any coalition of medical establishments can handle.

Policymakers, and especially the public, choose to ignore these kinds of consequences when speaking so casually and reflexively of nuclear retaliation. Neither the Americans nor anyone else will really want to care for thousands, perhaps tens of thousands, of horribly injured people in the remains of a state that has already used nuclear weapons against the United States or its friends. But many of the sick, injured, and destitute will be civilians, and the victorious powers will have no choice but to render whatever assistance they can.

In reality, where burns and other severe injuries will be beyond medical help, U.S. and allied military forces advancing into the enemy damage zones in the aftermath of a nuclear counterattack will have no humane choice but to euthanize the untreatable casualties on the spot. Such actions could retroactively make America’s nuclear retaliation seem violent beyond reason, perhaps even genocidal, to friends and enemies alike.

Analysts at the RAND Corporation in 2010 modeled a single ten-kiloton explosion (again, smaller than Hiroshima) at ground level in Seoul. They estimated that some 160,000 people would die or suffer serious injuries for miles downwind from fallout alone. RAND also pointed out that this single nuclear strike in the South would “vastly outstrip medical supply” and “could cause panic,” problems that would be far worse should the United States engage in multiple strikes in North Korea, where modern medical care is unavailable.

One or several nuclear explosions in the Middle East will replicate these problems across several nations with common land borders. In the Iranian case, the political impact of long-term radiation will be fractured and multiplied across a matrix of various cultures, political systems, and religious movements. Even a small retaliatory strike will mean at least some radioactive contamination and consequent social and physical disruption throughout the Arab Middle East, and Islamic radicals would no doubt welcome the anger and suffering that would persist long after the war’s end. As a practical matter, aside from injury to innocent civilians, the destruction or contamination of crucial sea lanes, ports, and other assets could make the tangible costs of whatever started the war seem tiny by comparison.

And What If the Enemy Leaders Survive?

Moreover, there is no guarantee that such a strike would succeed, and the risk of failure raises yet another question about nuclear retaliation: what if the United States relies on small, tightly targeted nuclear weapons, and the enemy leadership survives the retaliatory strike anyway?

This is not a trivial possibility. As a 2010 RAND study pointed out, the late North Korean leader Kim Jong-Il had “a history of disappearing during high-end provocations, presumably so that he [could not] be targeted,” and his son and the rest of the Kim coterie doubtless will take similar precautions. Nuclear targeting is not a trial-and-error process: if the object is to kill or disable the enemy leadership with nuclear weapons, there will be no second chance if the attack fails. One nuclear salvo is going to be difficult enough to plan and execute, and a second will be impossible, politically if not militarily.

One nuclear salvo is going to be difficult enough to plan and execute, and a second will be impossible, politically if not militarily.

Should some member of the Kim family and the rest of North Korea’s high command emerge alive and defiant from the damage of a U.S. nuclear retaliatory strike, the United States will have taken its nuclear shot and missed, much like the conventional “shock and awe” operation that tried to kill Saddam Hussein—and didn’t—on the eve of the 2003 invasion of Iraq. A nuclear blow against the enemy leadership must not fail the first rule of regicide: if one is to strike the king, one must kill the king.

All of these challenges undermine the credibility of nuclear threats against small states, not because they cannot be answered, but because the answers are unacceptable and the West’s potential enemies surely know it. Some of these problems, such as a public panic about radiation, are unavoidable but might not present an ultimate barrier to the retaliatory use of nuclear weapons.

Other concerns are far more daunting, chief among them that breaching the nuclear barrier will require policymakers to believe that they have been given nearly perfect intelligence, that there will be no mistakes in translating that information into meaningful nuclear targeting, and that the strikes themselves will never suffer some kind of operational failure or error. Meanwhile, the terrible consequences of collateral damage to innocent civilians have no solution at all. These choices, risks, and eventual costs will all have to be made and accepted if nuclear weapons are used in a regional conflict.

War is more than a series of immediate technical or political problems. It involves the taking of human life on a national scale. In the case of nuclear war, it also includes the possible destruction of cities and regions that are part of the common heritage of mankind. When thinking about a major war between peers such as the former Soviet Union and the United States, the strategic risk and moral anguish of these questions were often set aside in the name of maintaining the balance of terror. When considering nuclear war with small states, where U.S. national existence is not at stake, such restrictions cannot be so easily dismissed.

Adapted from “No Use: Nuclear Weapons and U.S. National Security” (University of Pennsylvania, 2014).