BECAUSE North Korea is a closed society, a visitor would have little or no chance of determining whether it possesses an atomic bomb. But there is another country that may know just how capable North Korea is of producing one -- Russia.
The Soviet Union played the decisive role in the development of North Korea's nuclear industry. Moscow provided and put into operation, in 1965, North Korea's first two-megawatt reactor; it trained more than 60 nuclear experts to service the reactor. When Pyongyang wanted to upgrade it, Russians assisted.
The Soviet Union also supplied Pyongyang with reactor fuel. Before the reactor was modernized in 1974, North Korea received a stock of 10 percent-enriched uranium; following modernization, the enrichment level rose to 80 percent.
Russia shipped about 4.5 pounds of uranium a year to Pyongyang, with the last shipment in 1991. Since then, Moscow has defied North Korean requests for additional shipments called for in a contract that officially remains in effect.
But the North Korean reactor, probably the government's only source of weapons-grade plutonium, is not likely to go out of business. During the two countries' period of nuclear cooperation, North Koreans stockpiled the Russian fuel, enough to keep the reactor going for some time.
Some Western experts estimate North Korea's plutonium reserves at three pounds. (An efficient nuclear charge requires around 22 pounds of plutonium.) According to Nikolay Arkhangelsky, a staffer at the Russian nuclear energy ministry who monitored North Korean-Russian cooperation, even this figure appears slightly exaggerated.
A skeptic might argue that North Korea may have chosen to manufacture a uranium bomb like the one used at Hiroshima. But do the North Koreans have the capacity to build such a bomb? Russian experts know that North Korea has uranium-ore reserves of 26 million tons, enough to produce 15,000 tons of uranium. The country has two uranium mines, in Pakchon and Pengasan, and two uranium-enrichment facilities.
But those two facilities are intended to extract uranium from uranium ore. Enriching extracted uranium with uranium-235 is quite a different matter. Only the five nuclear powers have weapons-grade uranium-enrichment technology, which is extremely expensive.
It was rumored that Pyongyang has brought a considerable amount of 35 percent-enriched uranium from a third country. Even so, the weight of a charge made with this relatively low-grade uranium would be 600 tons (based on the fact that a nuclear charge makes up 60 percent to 70 percent of a warhead's weight). It would be difficult to budge such a warhead, let alone hurl it at an enemy. After all, the Saturn 5 rocket, the world's most powerful missile, can carry a payload of only 135 tons.
A bomb made with 80 percent-enriched uranium would weigh about 10 tons. But Pyongyang lacks a vehicle to carry such a warhead. Indeed, its prospects for developing such an missile are not good, due to a shortage of skilled personnel.
But the key to North Korea's nuclear capability is its development of a device that explodes the nuclear payload. "Even if the North Koreans have produced a ton of plutonium, they have gone only 30 percent of the way toward the creation of an efficient nuclear weapon," says Arkady Brish, Russia's chief designer of nuclear charges. "The key is the nuclear explosive device."
Russians have known the importance of this device for a long time. After Nikita S. Khrushchev passed along the secret of uranium enrichment to China, the Chinese soon requested the secret technology for building the explosive device. Khrushchev was inclined to give them what they wanted; the relevant documents were loaded onto a railroad car for delivery to China. But following a Politburo debate, China's request was turned down. The documents were torched.
Thus, lacking a nuclear explosive device, North Korea probably lacks the bomb. How else to explain the absence of any test-site explosion in North Korea. What is more, there is no evidence that construction of a testing site is under way.
It would be absurd to claim that a country could build a nuclear explosive device of its own without staging at least one test explosion. But could the North Koreans conduct a secret, extremely low-power nuclear explosion that does not require the construction of a large testing site in the hope that foreign seismic stations might mistake it for a conventional explosion? Quite unlikely. The sophistication of seismic technology makes it possible to distinguish between a conventional and a nuclear -- even if very low power -- explosion.
True, the North Koreans could do without an explosive device and use their stock of plutonium as a radiological weapon, "the poor man's bomb." That is, they could put the plutonium inside a warhead and launch it on a missile. The fallout plutonium (it does not explode) could spread to cover a large area and do a lot of damage. But such a use of plutonium would be highly inefficient.
Truth be told, North Korea may be keeping inspectors out of its atomic facilities because once there, they could figure out that Pyongyang does not have the bomb. North Korea's bluff would be called, and everyone would realize that "the king has no clothes on."
Igor Morozov is an independent Russian journalist specializing in the nuclear industry.