A man in Seoul walks past a television report on North Korea's nuclear test. (Kim Hong-Ji / Courtesy Reuters)
In his State of the Union address, U.S. President Barack Obama described North Korea's recent nuclear test as a provocation that required a firm response. The intended audience for that provocation, though, is up for debate. Some commentators have posited that the test was a signal aimed at China, designed to demonstrate North Korea's independence from its great-power patron. Others think that Kim Jong-un was sending a message to the newly elected president of South Korea, Park Geun-hye. Still other North Korea experts have suggested that the test was actually meant for domestic consumption, to lift the sagging morale of a deprived public or for the regime to curry favor with the military. The intended North Korean signal is being analyzed and debated by U.S. government officials, who hold views across the spectrum.
A much simpler explanation exists. Pyongyang tested a nuclear device for the same reason it has been testing long-range missile designs: to see what works. In truth, the effort was less a signal than an attempt to master the technical capabilities that are vital to its nuclear deterrent.
This rationale should come as no surprise to those steeped in Cold War history. Between 1945 and 1992, the United States conducted 1,054 nuclear tests and fired an untold number of missiles. If the goal had merely been to show the Soviets that the United States meant business, testing nearly twice a month throughout the entire Cold War would have been overkill. In fact, Operation Sandstone -- a series of three tests at Enewetak Atoll in 1948 -- was not intended to warn off the Soviets as tensions rose over Berlin. Nor was the series of 48 underground tests launched in the summer of 1964 designed to impress the newly installed premier, Leonid Brezhnev. And the United States would not have conducted a dozen atomic blasts at its Nevada test site in the first half of 1977 -- including the Cove, Dofino, Marsilly, Bulkhead, Crewline, Forefoot, Carnelian, Strake, Flotost, Gruyere, Scantling, and Scupper detonations -- just because new President Jimmy Carter was vulnerable to right-wing criticism.
The United States did what it did because it needed its ultimate deterrent to actually work, and because the technical requirements of the nuclear mission continually changed. The ruins of Hiroshima and Nagasaki were evidence enough that the United States could destroy cities, but deterring the Soviet Union was a far greater challenge. If the Soviets had invaded Western Europe, for example, U.S. bombers would have had to penetrate alerted Soviet air defenses, identify Soviet ground forces and industrial centers, and attack them. Accordingly, U.S. bombers had to be highly maneuverable and able to carry multiple weapons, so the bombs themselves had to be lighter and smaller than the ones the United States used against Japan. The Soviets put another wrinkle in Washington's plans when they began to deploy large numbers of their own nuclear weapons. The United States needed to find a way to potentially destroy the Soviet arsenal on the ground. Eliminating those targets -- numerous and often hardened -- required even greater numbers of bombs, even lighter designs, and more accurate delivery systems. So the United States updated its designs and tested. And tested. And tested again.
Like the United States during the Cold War, North Korea has apparently decided that nuclear weapons are central to its national security strategy. With few friends, its conventional military forces outgunned, an economy in tatters, and facing off against a superpower prone to deposing dictatorships across the globe, the Kim regime set about building an operational nuclear arsenal. And just as NATO planned to thwart a Soviet invasion by striking targets in the Soviet Union and Eastern Europe, North Korea presumably plans to defend itself, should war erupt on the peninsula, by threatening U.S. regional allies and targets in the United States.
North Korea's mission requires small, lightweight warheads, and missiles that work -- and the only way to know that they work is to test them. So far, the weapons have proved unspectacular. The country's first nuclear test, conducted in 2006, was an embarrassment. Pyongyang had told the Chinese that the device would generate four kilotons of explosive power, but it ended up producing less than one. The second test in 2009 fared slightly better, producing between one and eight kilotons, although it is not known what size of a blast the North Koreans had sought. Moreover, Pyongyang has much more work to do before it can boast weapons that will actually fit on its missiles (which have been, themselves, a series of humiliating failures).