Solving the North Korean Nuclear Puzzle: Prologue

by David Albright

In 1987 U.S. analysts became suspicious that North Korea was building a large facility to separate plutonium at the Yongbyon Nuclear Center, about 100 kilometers north of Pyongyang.  Despite having signed the Nuclear Non-Proliferation Treaty (NPT), North Korea was suspected of seeking nuclear weapons.  Once finished, this facility, commonly called a reprocessing plant, would give North Korea the capability to make nuclear weapons. 

This development was alarming.  The Korean peninsula was already one of the world’s most dangerous Cold War flashpoints.  Armed with nuclear weapons, North Korea could change the course of a war with South Korea and the United States.  Absent war, North Korea could threaten the United States and its allies, force a costly military buildup, provoke nuclear proliferation by powers in the region, and damage the international nonproliferation regime.

U.S. satellite photos clearly showed the construction of a long, narrow structure that had several of the characteristics of a plutonium separation facility.  It was so massive that some worried that North Korea had embarked on a program to build a large nuclear weapons arsenal.

However, U.S. experts at that time differed over the true purpose of the facility.  It did not look like a typical reprocessing “canyon” with thick concrete walls to protect against the release of highly radioactive materials.  “Some really good imagery analysts thought it was not a reprocessing plant,” said a participant in this debate in the late 1980s.  The walls of the concrete structures inside the facility were not as thick as expected for such a plant.  In addition, the outer walls of the building had windows, which was unusual, since plutonium separation facilities are typically designed to reduce chances of a release of radioactivity.  Windows do not provide much protection in the event of routine releases, let alone during an accident.  In addition, reprocessing facilities can experience explosions, and thus the outer walls should be built to withstand such explosions.  Finally, U.S. imagery analysts never saw a shipment of spent fuel enter the building.

In interviews with the author in 1991, senior U.S. officials explained the reasoning of some U.S. analysts who thought the facility was actually a decoy.  They reasoned that the facility was too obvious; its purpose was to suggest a nuclear capability that North Korea did not have, in an attempt to gain political leverage.  They argued that North Korea was committed to separating plutonium, but the actual separation facility was elsewhere. 

By 1991, however, most analysts had come to believe that the facility was built to separate plutonium. But a new controversy arose over estimates of when the facility would be finished.  One State Department official told me in 1991 that the outside of the building was complete, but he reasoned that the facility would be similar to Western reprocessing plants, and therefore elaborate stainless steel piping would need to be installed before it could operate, a step that he said would take several years.  But this U.S. official added that, because so little was known, U.S. analysts would not be greatly surprised if the plant were to begin operating immediately.

In early 1992, CIA officials believed that North Korea could be close to having enough plutonium for a nuclear weapon.  On February 25, 1992, CIA Director Robert Gates told the House Foreign Affairs Committee, in response to questions, that North Korea was a “few months to a couple of years” from having a nuclear weapon.  The CIA also thought that North Korea was hiding some of its nuclear efforts; on February 28, 1992 the Washington Post reported that a U.S. official said that large trucks had been “hauling things away” from the reprocessing plant.

IAEA Inspections

When Hans Blix, then the Director General of the International Atomic Energy Agency (IAEA), led a delegation to the Yongbyon site in May 1992, the Agency quickly determined that the building contained a large plutonium separation plant.  More startling, North Korean officials told the delegation the plant had already separated a small amount of plutonium. 

This visit followed North Korea finally bringing into force its safeguards agreement in April 1992, as required under the NPT, which it had signed in 1985.  The NPT requires signatories to conclude a safeguards agreement within 180 days of accession to the treaty, but North Korea stalled negotiating its safeguards agreement for years, signing it only after tensions on the peninsula had been greatly reduced, and the United States announced it would remove all its nuclear weapons from South Korea.

On the IAEA’s historic visit, North Korean officials took the delegation on a tour of North Korea’s major nuclear installations.  IAEA officials went inside the still-incomplete reprocessing building, which North Korea called the “Radiochemical Laboratory.”

The ambiguous indicators seen by U.S. imagery analysts reflected North Korea’s decision to choose a different, albeit less safe, design for a reprocessing plant.  This design was far simpler than modern Western facilities; in fact, it was more like the first primitive plants built in the West in the 1940s and early 1950s.  It was learned later that spent fuel had been moved to the separation building from a nearby operating reactor in a truck at night.

The IAEA’s visit cleared up another controversy about North Korean nuclear capabilities.  U.S. analysts had worried that the complex of facilities to the south of the plutonium separation building housed a uranium enrichment plant for producing weapon-grade uranium, another nuclear explosive material.  The suspect enrichment plant turned out to be a complex to process uranium and manufacture nuclear fuel for reactors.

This visit also showed that the IAEA intended to be more inquisitive than it had been in the past.  While walking from one facility to another, IAEA officials noticed a building with a stack or exhaust.  They asked their North Korean hosts to identify the building, as it had not been listed on North Korea’s initial safeguards declaration. A North Korean said that the building produced isotopes for medicine and agriculture, and thus North Korea did not have to list this building on its declaration.  Nonetheless, because this capability implied that the building would have hot cells, and thus could theoretically separate plutonium, Blix asked to visit the building.  The North Koreans said they did not have a key, but Blix said they would wait while one was found.  After about an hour, the North Koreans found the key to the building, and the delegation was shown the Isotope Production Laboratory.  Later, IAEA inspectors would learn that North Korea’s first plutonium separation experiments were done in this building.

Blix’s trip showed the value of on-site inspections.  For many, this trip raised hopes that North Korea was abandoning any plans to make nuclear weapons; however, problems soon developed.  By analyzing isotopic samples taken during ad hoc inspections in the summer and fall, the IAEA identified inconsistencies in North Korea’s description of its past nuclear activities and discovered evidence of North Korean efforts to keep some nuclear activities secret.  Inspectors grew increasingly suspicious that North Korea had separated considerably more plutonium than it had declared officially to the IAEA in its initial safeguards report.

Much of the evidence of inconsistencies resulted from the new inspection methods deployed in Iraq after the Persian Gulf War.  The IAEA had failed to detect Iraq’s massive pre-war secret nuclear weapons effort, and this embarrassment led the IAEA Board of Governors to require the IAEA to conduct a more thorough investigation of the completeness of a state’s declaration.  This task would prove to be difficult and time-consuming in a country with a large, pre-existing nuclear program.

IAEA member states also decided to declassify and share more sophisticated monitoring techniques.  In the end, these tools were necessary because North Korea was believed to have taken extraordinary efforts to remove traces of plutonium from the Radiochemical Laboratory, including cleaning and grinding down the metal surfaces of glove boxes.  Nonetheless, inspectors were able to swipe innocuous looking clothes along uncleaned surfaces and in “nooks and crannies” in the glove boxes and the adjacent areas.  After analysis, these swipe samples revealed the presence of minute quantities of plutonium, far below levels that would have been detected under traditional safeguards.  Analysis of this plutonium and other plutonium samples was critical to the IAEA’s case that North Korea had not provided a correct or complete declaration, and had separated more plutonium than it had declared.

Another major change was that member states decided to provide the IAEA with significantly more information about North Korean nuclear activities.  Some of this information was learned by intelligence methods, including satellite surveillance.  Armed with new analytical tools and greatly expanded assistance from member states, the IAEA was able to uncover a wide range of inconsistencies in North Korea’s declaration.  Despite catching North Korea off guard and assembling an impressive amount of evidence, the IAEA could not determine how much plutonium North Korea had separated.  Was it enough for one or two nuclear weapons, as the CIA was increasingly asserting?  Or was it less than enough for one nuclear weapon?  Even today, only the North Koreans know the answer.

Averting a Large Nuclear Arsenal

While questions about North Korea’s past separation could not be answered, the question of future plutonium separation had an ominous implication.  The inspections confirmed that North Korea was putting together a large nuclear infrastructure, including reactors that would be able to produce enough plutonium for tens of nuclear weapons per year.  Keeping North Korea from realizing this goal became a U.S. priority.  Ultimately, this objective justified the 1994 Agreed Framework between the United States and North Korea that achieved a suspension of activities at North Korea’s indigenous gas-graphite reactors and associated facilities in exchange for modern light-water reactors that are now in early stages of construction.

If the Agreed Framework had not “frozen” North Korea’s nuclear program, including a ban on reprocessing, North Korea would have put into operation three gas-graphite reactors by the year 2000, all of which could have made weapon-grade plutonium.  In total, by about 2000 North Korea could have accumulated 300-400 kilograms of weapon-grade plutonium.  Assuming that five kilograms is enough for a nuclear weapon, this amount of plutonium is enough for about 60-80 nuclear weapons.

Once fully operational, these three reactors could have produced approximately 210-280 kilograms of weapon-grade plutonium per year, or enough for 40-55 nuclear weapons a year.  North Korea’s plutonium separation plant at Yongbyon could have separated about half of this plutonium.  The rest could have been separated in an expanded or new plant.

Getting to a Settlement Without War

In 1993, the IAEA Board of Governors, for the first time in the Agency’s history, called for a “special inspection” in North Korea to investigate the discrepancies between known data and North Korea’s account of its nuclear history.  Pyongyang refused, withdrew from the IAEA, and declared its intent to withdraw from the NPT.  Soon thereafter, it declared its NPT obligation to be in a “suspended” state-a legal assertion the IAEA did not accept.

The Agreed Framework’s freeze on North Korea’s nuclear program occurred only after the United States and North Korea came perilously close to war.  In May and June 1994, North Korea refused to allow the IAEA to sample the spent fuel that North Korea was discharging from the small gas-graphite reactor at Yongbyon, and thus the IAEA could not determine how much plutonium North Korea had produced in this reactor.  The sampling method would have been able to determine if North Korea had secretly unloaded much of the fuel in this reactor in 1989, giving North Korea enough plutonium for up to one or two nuclear weapons.  As a result, the United States ended its initial efforts to negotiate with North Korea and sought UN Security Council sanctions against North Korea.  Meanwhile, in response to North Korea’s nuclear ambition, the United States began serious preparations for war.

As the crisis worsened, IAEA inspectors kept watch at the reactor site to provide assurances that the fuel remained there and was not sent to the reprocessing plant.  Regardless of the controversy over past plutonium separation, the irradiated fuel contained enough plutonium for five or six nuclear weapons. 

Initially, Blix had had a strong predisposition to withdraw inspectors on the grounds that the IAEA’s continued presence in the face of North Korea’s intransigence would legitimize its behavior and imply IAEA “flexibility” regarding North Korea’s compliance with its obligations.  Under U.S. urging, however, he came to accept the importance of remaining at the reactor site.  According to Ambassador John Ritch, U.S. Representative to the IAEA in Vienna, Blix subordinated his concern to a more compelling duty to serve as the world’s “eyes and ears” in a situation where IAEA inspectors, in spite of wrongdoing and indeed because of it, could provide invaluable and otherwise unobtainable knowledge.

Voices in Washington increasingly called for a U.S. military buildup in the region.  Some called for a preemptive military strike against North Korean nuclear facilities.  A senior U.S. official, involved at that time, said that the United States was stampeding itself toward war.

Concerned about the increasing risk of war, former President Jimmy Carter visited North Korea in June 1994.  The visit’s major accomplishment was getting the United States and North Korea back to the negotiating table, culminating in the conclusion of the Agreed Framework a few months later. 

As the crisis escalated, Ritch advocated in secret cables from Vienna that the goal of obtaining a complete account of a small and uncertain amount of nuclear material in North Korea should be subordinated to the aim of controlling the future of the large and certainly dangerous amount of nuclear fuel being unloaded from North Korea’s main reactor.  The “ancestry” of Pyongyang’s nuclear program, he argued, was far less important than its “destiny.”  Carter’s visit solidified this view: learning if North Korea had already produced enough plutonium for up to one or two nuclear weapons was far less urgent than preventing North Korea from separating enough plutonium for five to six nuclear weapons.

For now, North Korea has been averted from acquiring a large nuclear arsenal.  The June 2000 historic summit between the leaders of North and South Korea may have eliminated the chance of war on the peninsula. 

But it remains unclear whether North Korea has enough plutonium for up to one or two nuclear weapons, or is building new facilities to convert this material into nuclear weapons or produce new material for weapons.  Uncertainty continues to plague assessments of the status of North Korea’s nuclear weapons program.

Under the Agreed Framework, North Korea has agreed that it will come into full compliance with its safeguards agreement with the IAEA before any significant nuclear components for the first light water reactor are delivered from the West.  That date is approaching. 

A major uncertainty is whether North Korea will, in the end, comply with the Agreed Framework by demonstrating verifiably that it does not have nuclear weapons or the capability to make them.  The question of the amount of plutonium North Korea produced must finally be settled; otherwise, the IAEA cannot determine if North Korea is in compliance with its safeguards agreement. 

Succeeding under the timetable defined in the Agreed Framework while avoiding another major crisis, and possibly the “un-freezing” of the Yongbyon facilities, will require cooperation and coordination among the IAEA, the United States, South Korea, Japan, China, and many other countries.  It will also require the vigilance of the people of the world, and leaders like Jimmy Carter, who played a pivotal role in assuring we did not go to war back in 1994.