Ever since bows and arrows came on the scene 15,000 years ago, the spread of military technology has shaped the nature of conflicts. Some new technologies rapidly became commonplace; others failed to spread or were successfully banned. The historical lessons to be learned from weapons proliferation are useful to reflect on as we figure out how to deal with North Korea.
Let's start by considering an episode in New Zealand history known as the Musket Wars. New Zealand's original inhabitants, a Polynesian people known as the Maori, possessed stone and wooden weapons but lacked guns. Maori tribes were chronically embroiled in fierce warfare with one another. But that warfare did not produce mass slaughters because all tribes were equally matched in their weapons, which were useful only for fighting at close quarters.
Those limitations began to change as European traders started arriving in New Zealand in the early 19th century. Until 1815, the Napoleonic Wars meant that Europeans needed all the weapons they produced. But after Napoleon's surrender, a surplus of guns became available for other purposes, such as selling to Maoris.
By 1818, the Nga Puhi tribe at the north end of New Zealand, where the first European trading stations had been set up, had acquired enough muskets to start using them in battle. This began a period of carnage that lasted until 1835. Intertribal musket wars killed about one-quarter of the Maori population -- more people than New Zealand would lose to trench warfare and poison gas in World War I.
At first, tribes with guns used them to settle accounts with neighboring traditional enemies who had the misfortune still to be gunless. Then, as the Maoris realized the power of their new weapons, gun-possessing tribes began traveling up to 1,000 miles to attack tribes with which they had no quarrel, just to show off power and capture slaves. Tribes without guns desperately tried to acquire them, because their survival was now dependent on firepower. Some tribes got the weapons, mounted successful defenses and went on to become attackers themselves. Other tribes were either wiped out or enslaved.
Then something strange happened. As guns spread, casualties declined. Eventually, when all surviving tribes were armed, there were no more easy victories, and Maori warfare, though still chronic, settled back down to something like its previous level.
The Musket Wars illustrate the potential instability of a situation in which a potent new technology is unevenly distributed. The wars began when only a few tribes had guns, and they ended when all had them. If nukes follow a similar course, North Korea's going nuclear could trigger a desperate scramble by other countries to acquire the weapons in self-defense.
But history also tells us that the spread of military technology isn't inevitable. Some innovations didn't proliferate; they remained restricted or were abandoned. A prime recent example is nuclear weapons themselves. They have been developed and openly tested by only five world powers (the U.S., Russia, China, Britain and France) and two regional powers (India and Pakistan). Only one other regional power (Israel) is believed to have built them secretly and to possess them today. To the pleasant surprise of those of us old enough to remember the Cold War, nuclear weapons have never been used since their debut in August 1945.
There have been other cases in which new weapons failed to become widespread. During World War I, the German army introduced poisonous chlorine, phosgene and mustard gases. In each case, the allies first expressed moral revulsion, then hastened to deploy the same gas themselves. After the war, by mutual agreement, poison gas was banned. Its sole subsequent use was by Iraq, with devastating effect, against Iran and against its own Kurdish minority. A naval arms race was interrupted by the Washington Treaty of 1922, when the countries with the largest navies agreed to limit the size and number of their battleships and aircraft carriers. They maintained that agreement until a new naval arms race broke out in the 1930s. Highly destructive, soft-nosed dum dum bullets, which expand on contact, were used only briefly before being banned and have not been reintroduced. Japan, which acquired guns in 1543 and by 1600 had more and better firearms than any other country, subsequently renounced guns unilaterally for some time thereafter.
Several reasons are at the core of why some but not other technologies spread. Poison gas was found not to provide a military advantage in World War I: English and French chemical factories could make it as easily as could German factories, and shifts in wind direction often blew it back over its users' own lines. In contrast, Iraq calculated correctly that Iran lacked a chemical industry capable of rapid response. Battleship fleets were extremely expensive to build and maintain, so saw little actual use in World War I, and the major naval powers were only too pleased to be spared the expense of them as long as their likely opponents were equally abstemious. Japan's samurai hated guns because they allowed clumsy peasants to kill a graceful sword-wielding samurai. For several reasons, nuclear weapons have spread slowly and have not been used since their initial horrible debut. Nuclear powers have understood the importance of nonproliferation. Mutual deterrence has worked. And nuclear weapons are expensive -- both morally and financially.
History also illustrates that a technology can be destabilizing even if it rarely or never sees action, like the battleships at the core of the arms race that culminated in World War I. Often, the mere possession of military power and dangerous weapons by one side is enough to make an opponent back down without a fight, as happened when Hitler's Germany bloodlessly took over Austria in 1938 and Czechoslovakia in 1939, and when Czechoslovakia yielded to the Soviet Union in 1968.
What will happen when (I wish I could say "if") North Korea tests a nuke? It's tempting to say that since eight countries already have nuclear weapons that they've refrained from using, a ninth shouldn't cause too much worry. But the ninth country differs fundamentally from the first eight. The Big Five have never used their nukes against each other, because their leaders have had enough maturity to recognize a standoff, and to wish to avoid the certainty of mass casualties of their own citizens in a retaliatory response. Everyone understands that India and Pakistan would use their nukes "only" against each other, and that Israel's nukes are intended "only" as a weapon of last resort against an attack by Arab neighbors. North Korea differs in its history of provocative behavior, unpredictability and willingness to inflict great suffering on its own citizens.
It would be rational to assume that North Korea would brandish its nukes only as a bargaining chip to extract concessions, but we can't assume rationality with Kim Jong Il. The mere existence of North Korean nukes could be destabilizing: as a grave direct threat to South Korea, Japan and the U.S.; as an example to many other states presently without nukes but with the capacity to build them; and as a likely source of nuclear weapons for sale to even more dangerous buyers. It could unleash a new kind of Musket Wars.
Should the world act preemptively to stop North Korea? We can't know for sure what it would do with nuclear weapons, or whether other states will follow its example. Our decision about how to respond must rest on uncertainties. North Korean nuclear weapons are a much bigger threat to world stability than Saddam Hussein's chemical and biological arms, and a threat equal to that of the nuclear weapons he hoped to build with his reactor. In retrospect, we all are fortunate that Israel preemptively destroyed Iraq's nuclear reactor. Conversely, England and France could have easily and cheaply prevented World War II by acting preemptively when Hitler militarized the Rhineland in 1936. As British and French inaction then illustrates, abstaining from striking preemptively is not morally virtuous when it leads to something infinitely worse.
So a case can be made for preemptively taking out North Korea's nuclear weapons facilities. But such action would almost certainly trigger a North Korean conventional attack on Seoul and on U.S. forces just across the DMZ, with unpreventable casualties estimated at 100,000 in the first week. Perhaps the North Koreans really are just blustering and just want to be bought off with food shipments. Perhaps they are serious. To balance these risks and decide on a course of action will require success on the part of America's leaders in achieving broad consensus among Americans and among the world's other peoples. Alas, those successes have conspicuously escaped our leaders in confronting Iraq. Can they be more persuasive about North Korea?