UNITED STATES negotiators nudging North Korea toward forgoing nuclear-weapons development are operating in a maze of uncertainty about what Pyongyang's clandestine program already has achieved.
The outside world cannot be sure how much plutonium for fueling atomic warheads the North Koreans already have produced, whether they have sold any to other countries, or whether they have produced any nuclear weapons of their own.
The operating nuclear reactor in North Korea is of five-megawatt capacity, built in the 1980s. In the public domain is the fact that it was shut down for 100 days in 1989 for reprocessing of its core units. What is not generally known is that the reactor has been shut down for reprocessing at least three times since then.
Each reprocessing permits the production of five to 10 kilograms of plutonium - enough to build a nuclear bomb. Theoretically, the North Koreans could have built one bomb per year since 1989.
Two other, much bigger reactors are under construction. One is a 50-megawatt reactor due to be finished in 1995, the other a 100-megawatt reactor due to be finished around 2000.
All three reactors are of graphite-moderated, gas-cooled design capable of producing substantial quantities of plutonium for nuclear weapons development. The US would like to see them replaced by light-water reactors, which produce less plutonium. To curb North Korea's capacity for weapons development, the existing five-megawatt reactor would need to be closed, and the 50-megawatt and 100-megawatt reactors under construction would need to be rebuilt from scratch.
The North Koreans have an extensive and sophisticated network of underground tunnels that they have displayed to at least one international nuclear expert. While it is possible that there is another, hidden nuclear reactor, reactors are huge; experts consider it unlikely that one exists underground. It is possible that there is an underground reprocessing plant that could operate undetected by US spy satellites.
In other words, as the US gropes toward an agreement that might curb and regulate North Korea's future nuclear program, there is not much to be done - short of an American invasion - to eliminate what already has been accomplished by Pyongyang's clandestine program.
The problem is not only whether North Korea has been able to construct a nuclear warhead - threatening enough to South Korea, Japan, and others. It is whether North Korea has sold, or will sell, plutonium to such international troublemakers as Libya, Iraq, or Iran for the hard currency it needs to keep its tottering economy stable.
Ironically, though the cold war posed the threat of catastrophic nuclear confrontation, its demise has made the world more vulnerable to nuclear proliferation among smaller regional powers, freelancers, and crime syndicates.
While the Soviet Union was intact and at its peak, it maintained strict control over its nuclear material and arsenal. As the country disintegrated, some of this arsenal was dispersed and may have fallen into the hands of freelancing military men or powerful crime gangs. The process of arms reduction and destruction worked out with the Americans also has afforded the opportunity for the diversion of nuclear material from these redundant weapons.
Louis J. Freeh, director of the Federal Bureau of Investigation, says this trading in weapons-grade nuclear material is a major threat to US security. He visited Moscow last month to try to coordinate the attack on Russian organized-crime gangs attempting to trade in nuclear material.
Even so, the traffic is ongoing. Last week German security personnel seized more than a pound of plutonium 239 being smuggled into Munich on a Lufthansa flight from Moscow. That is about 1/20th of the amount needed to construct a bomb. This is just one of four known seizures of plutonium shipments out of Russia since May. At least one of them is believed to have been destined for Iraq.
Clearly there are sellers and buyers of material that can be used to build nuclear warheads. In this environment it is important to seal off the potential supply from North Korea, which until now has been aloof, unpredictable, and hostile to the US.
The Clinton administration should be cautiously optimistic that the new North Korean leadership appears willing to deal - albeit at the price of diplomatic recognition and substantial US aid. President Clinton should also be mindful of North Korea's past duplicity and broken promises, and the fact that the US is still uncertain what Pyongyang's clandestine program has already produced.