Shortly after North Korea exploded its second nuclear device in three years on Monday morning, it released a statement explaining why. "The republic has conducted another underground nuclear testing successfully in order to strengthen our defensive nuclear deterrence." If the Obama Administration hopes to dissuade Pyongyang from the nuclear course it seems so hell bent on pursuing, Washington must understand just how adroitly nuclear arms do appear to serve North Korea's national security. In other words, perhaps we should recognize that they mean what they say.
From the dawn of history until the dawn of the nuclear age, it seemed rather self-evident that for virtually any state in virtually any strategic situation, the more military power one could wield relative to one's adversaries, the more security one gained. That all changed, however, with Alamogordo and Hiroshima and Nagasaki. During the Cold War's long atomic arms race, it slowly dawned on "nuclear use theorists" -- whom one can hardly resist acronyming as NUTS -- that in the nuclear age, security did not necessarily require superiority. Security required simply an ability to retaliate after an adversary had struck, to inflict upon that opponent "unacceptable damage" in reply. If an adversary knew, no matter how much devastation it might inflict in a first strike, that the chances were good that it would receive massive damage as a consequence (even far less damage than it had inflicted as long as that damage was "unacceptable"), then, according to the logic of nuclear deterrence, that adversary would be dissuaded from striking first. What possible political benefit could outweigh the cost of the possible obliteration of, oh, a state's capital city, and the leaders of that state themselves, and perhaps more than a million lives therein?
Admittedly, the unassailable logic of this "unacceptable damage" model of nuclear deterrence - which we might as well call UD -- failed to put the brakes on a spiraling Soviet/American nuclear arms competition that began almost immediately after the USSR acquired nuclear weapons of its own in 1949. Instead, a different model of nuclear deterrence emerged, deterrence exercised by the capability completely to wipe out the opponent's society, "mutually assured destruction," which soon came to be known to all as MAD. There were other scenarios of aggression -- nuclear attacks on an adversary's nuclear weapons, nuclear or conventional attacks on an adversary's closest allies (in Western and Eastern Europe) -- that nuclear weapons were supposed to deter as well. However, the Big Job of nuclear weapons was to dissuade the other side from using their nuclear weapons against one's own cities and society, by threatening to deliver massive nuclear devastation on the opponent's cities and society in reply. "The Department of Defense," said an Ohio congressman in the early 1960s, with some exasperation, "has become the Department of Retaliation."
Nevertheless, those who engaged in an effort to slow the arms race often employed the logic of UD in their attempts to do so. "Our twenty thousandth bomb," said Robert Oppenheimer, who directed the Manhattan Project that built the world's first atomic weapons, as early as 1953, "will not in any deep strategic sense offset their two thousandth." "Deterrence does not depend on superiority," said the great strategist Bernard Brodie in 1965. "There is no foreign policy objective today that is so threatened," said retired admiral and former CIA director Stansfield Turner in 1998, "that we would ... accept the risk of receiving just one nuclear detonation in retaliation."
Consider how directly the logic of UD applies to the contemporary international environment, to the twin nuclear challenges that have dominated the headlines during most of the past decade, and to the most immediate nuclear proliferation issues now confronting the Obama Administration. Because the most persuasive explanation for the nuclear quests on which both Iran and North Korea have embarked is, indeed, the notion that "deterrence does not depend on superiority." Deterrence depends only an ability to strike back. Iran and North Korea appear to be seeking small nuclear arsenals in order to deter potential adversaries from launching an attack upon them -- by threatening them with unacceptable damage in retaliation.
Neither North Korea nor Iran could hope to defeat its most powerful potential adversary -- the United States -- in any kind of direct military confrontation. They cannot repel an actual attack upon them. They cannot shoot American planes and missiles out of the sky. Indeed, no state can.
However, what these countries can aspire to do is to dissuade the American leviathan from launching such an attack. How? By developing the capability to instantly vaporize an American military base or three in Iraq or Qatar or South Korea or Japan, or an entire U.S. aircraft carrier battle group in the Persian Gulf or the Sea of Japan, or even an American city on one coast or the other. And by making it implicitly clear that they would respond to any kind of assault by employing that capability immediately, before it's too late, following the venerable maxim: "Use them or lose them." The obliteration of an entire American military base, or an entire American naval formation, or an entire American city, would clearly seem to qualify as "unacceptable damage" for the United States.
Moreover, to deter an American attack, Iran and North Korea do not need thousands of nuclear warheads. They just need a couple of dozen, well hidden and well protected. American military planners might be almost certain that they could take out all the nuclear weapons in these countries in some kind of a dramatic lightning "surgical strike." However, with nuclear weapons, "almost" is not good enough. Even the barest possibility that such a strike would fail, and that just one or two nuclear weapons would make it into the air, detonate over targets, and result in massive "unacceptable damage" for the United States, would in virtually any conceivable circumstance serve to dissuade Washington from undertaking such a strike.
In addition, it is crucial to recognize that Iran and North Korea would not intend for their nascent nuclear arsenals to deter only nuclear attacks upon them. If the entire nuclear arsenal of the United States disappeared tomorrow morning, but America's conventional military superiority remained, it still would be the case that the only possible military asset that these states could acquire, to effectively deter an American military assault, would be the nuclear asset.
The "Korean Committee for Solidarity with World Peoples," a mouthpiece for the North Korean government, captured Pyongyang's logic quite plainly just weeks after the American invasion of Iraq in March 2003. "The Iraqi war taught the lesson that ... the security of the nation can be protected only when a country has a physical deterrent force ..." Similarly, a few weeks earlier, just before the Iraq invasion began, a North Korean general was asked to defend his country's nuclear weapons program, and with refreshing candor replied, "We see what you are getting ready to do with Iraq. And you are not going to do it to us."
It really is quite a remarkable development. North Korea today is one of the most desperate countries in the world. Most of its citizens are either languishing in gulags or chronically starving. And yet -- in contrast to all the debate that has taken place in recent years about whether the United States and/or Israel ought to launch a preemptive strike on Iran -- no one seems to be proposing any kind of military strike on North Korea. Why not? Because of the mere possibility that North Korea could impose unacceptable damage upon us in reply.
Perhaps the most remarkable thing about UD is that it seems every bit as effective as MAD. North Korea today possesses no more than a handful of nuclear warheads, and maintains nothing like a "mutual" nuclear balance with the United States. In addition, the retaliation that North Korea can threaten cannot promise anything like a complete "assured destruction." To vaporize an American carrier group in the Sea of Japan, or a vast American military base in South Korea or Japan, or even an American city, would not be at all the same thing as the "destruction" of the entire American nation - as the USSR was able to threaten under MAD.
And yet, MAD and UD, it seems, exercise deterrence in precisely the same way. Astonishingly, it seems that Washington finds itself every bit as thoroughly deterred by a North Korea with probably fewer than 10 nuclear weapons as it did by a Soviet Union with 10,000. Although UD hardly contains the rich acronymphomaniacal irony wrought by MAD, it appears that both North Korea and Iran intend now to base their national security strategies solidly upon it.
There is very little reason to suppose that other states will not soon follow their lead.
President Obama, of course, to his great credit, has not only made a nuclear weapon-free Iran and North Korea one of his central foreign policy priorities, he has begun to chart a course toward a nuclear weapon-free world. In a groundbreaking speech before a huge outdoor rally in Prague on April 5th, he said, "Today, I state clearly and with conviction America's commitment to seek the peace and security of a world without nuclear weapons." (Unfortunately, he followed that with the statement that nuclear weapons abolition would not "be achieved quickly, perhaps not in my lifetime," suggesting that neither he nor the nuclear policy officials in his administration fully appreciate the magnitude and immediacy of the nuclear peril. Do they really think the human race can retain nuclear weapons for another half century or so, yet manage to dodge the bullet of nuclear accident, or nuclear terror, or a nuclear crisis spinning out of control every single time?)
The one thing we can probably say for sure about the prospects for universal nuclear disarmament is that no state will agree either to abjure or to dismantle nuclear weapons unless it believes that such a course is the best course for its own national security. To persuade states like North Korea and Iran to climb aboard the train to abolition would probably require simultaneous initiatives on three parallel tracks. One track would deliver foreign and defense policies that assure weaker states that we do not intend to attack them, that just as we expect them to abide by the world rule of law they can expect the same from us, that the weak need not cower in fear before the strong. Another track would deliver diplomatic overtures that convince weaker states that on balance, overall, their national security will better be served in a world where no one possesses nuclear weapons, rather than in a world where they do--but so too do many others. And another track still would deliver nuclear weapons policies that directly address the long-simmering resentments around the world about the long-standing nuclear double standard, that directly acknowledge our legacy of nuclear hypocrisy, and that directly connect nuclear non-proliferation to nuclear disarmament.
The power decisively to adjust all those variables, of course, does not reside in Pyongyang or Tehran. It resides instead in Washington.
 The Washington Post, May 25, 2009.
 Quoted in Daniel Lang, An Inquiry Into Enoughness: Of Bombs and Men and Staying Alive (New York: McGraw-Hill, 1965), p. 167.
 Quoted in Ibid., p. 38.
 Bernard Brodie, Strategy in the Missile Age (Princeton, NJ: Princeton University Press, 1971 -- first published in 1965), p. 274, quoted in Sarah J. Diehl and James Clay Moltz, Nuclear Weapons and Nonproliferation: A Reference Handbook (Santa Barbara, California: ABC-CLIO, 2002), p. 34.
 Quoted in The Nation, Special Issue Containing Jonathan Schell's interviews with several nuclear policy professionals and intellectuals, February 2/9, 1998, p. 40.
 Quoted in Securing Our Survival: The Case for a Nuclear Weapons Convention, Tilman Ruff and John Loretz, eds. (Boston: IPPNW, 2007), p. 37.
 Don Oberdorfer, PBS, The News Hour with Jim Lehrer, October 9, 2006, quoted in Jonathan Schell, The Seventh Decade: The New Shape of Nuclear Danger (New York: Henry Holt, 2007), p. 141.