To read the seismic signal sent from an abandoned coal mine in the mountains of North Korea's coast, you must first recognize that it represents four major failures, two grave dangers, and one big opportunity.

The apparent explosion of a nuclear device, coming after two decades of trying to stop North Korea from achieving this goal, is a manifest failure of policy on four fronts -- a failure of U.S. nuclear non-proliferation policy, a failure of international diplomacy, a failure of Chinese leadership and a failure of South Korea's strategy of engaging the North.

Having failed so completely, the world now faces two grave dangers. The first is the very real threat of war on the Korean Peninsula, triggered by a series of escalatory actions in the wake of the bomb test. The second is the danger that North Korea will proliferate its nuclear technology, materials or know-how to others -- not the least to another nuclear hopeful, Iran.

But there remains a lone and tenuous opportunity. Having removed all ambiguity about its nuclear ambitions, North Korea may finally have created a common sense of threat that will galvanize the kind of concerted international action that so far has been absent.

THE FOUR FAILURES

Non-proliferation failure

The United States has spent two decades trying to stop North Korea from going nuclear, a turbulent period of crisis and negotiation that even went to the brink of war. At least three administrations confronted this problem and none, certainly not the Bush administration, can escape blame.

North Korea agreed to sign the Nuclear Non-Proliferation Treaty (NPT) in 1985, but it stalled before signing an agreement with the International Atomic Energy Agency (IAEA) in 1992 to place its nuclear facilities under international safeguards and inspections. During that time the North Koreans reprocessed some spent fuel from their reactor into plutonium - an amount that American intelligence believes was enough for building one or two warheads.

North Korea's resistance to full inspections, while it kept pulling spent fuel rods out of its reactor, provoked a crisis in 1994 and led the Clinton administration to ready military forces to strike the North's nuclear facilities. In a last-minute deal, North Korea froze its reactor and reprocessing facilities, effectively halting plutonium production under IAEA supervision. In exchange, the United States, Japan, South Korea and others agreed to construct two light-water reactors for North Korea and to supply fuel oil until the reactors came online.

The deal was troubled from the start. Neither party was satisfied with the compromise or the way it was to be implemented. By the late 1990s, the North had begun a secret effort to acquire uranium-enrichment technology from Pakistan and, in 1998, tested a long-range ballistic missile. Despite this, the plutonium freeze remained in place. But it did not survive the Bush administration.

The Bush administration came into office challenging the value of the agreement and froze contacts with the North. After receiving intelligence showing moves to build enrichment facilities, it confronted North Korean officials at an acrimonious meeting in Pyongyang in October 2002.

The United States halted fuel shipments a month later, and, in early 2003, the North Koreans expelled IAEA inspectors and withdrew from the Non-Proliferation Treaty. They proceeded to reprocess the fuel rods they had stored for a decade, producing enough plutonium, intelligence estimates say, for four to six nuclear warheads. In February 2005, the North Koreans announced they had manufactured nuclear weapons. Last week, they apparently made good on that declaration.

Blame aside, North Korea's emergence as the world's ninth nuclear power may be the most serious failure in non-proliferation history. Unlike India and Pakistan, which remained outside the system of international treaties, North Korea acted in defiance of those controls. Who might be next?

Diplomatic failure

Unlike Iraq, the attempt to stop North Korea's nuclear program has relied on the tools of diplomacy, accompanied by economic incentives and coercive sanctions.

But serious questions have been raised from the start about the sincerity and methods of the diplomatic efforts, particularly on the part of the United States and North Korea. The Bush administration has insisted -- and the president continues to make this argument -- that direct talks with North Korea do not work. Pyongyang has tried to frame everything as an issue with Washington, undermining talks that involved others, including South Korea.

Bush's stance lends credibility to those who charge the administration seeks "regime change," not a compromise that it believes will lend legitimacy to Kim Jong Il. The North Koreans now appear to have used the talks to buy time and build bombs.

Diplomacy has, at American insistence, consisted of six-party talks, held under Chinese auspices and including both Koreas, Japan and Russia. In truth, little real negotiating went on at these gatherings, at least until the last full round of talks in September 2005. In contrast to the thousands of hours of negotiations between Americans and North Koreans that led to the 1994 deal, there have been only tens of hours of actual give and take.

It is intriguing that the September agreement on a statement of principles for denuclearization came only after the State Department's chief negotiator was finally allowed to talk to his North Korean counterpart at length. Even then, their agreement evaporated almost immediately as they dueled publicly over the deal's meaning. American financial sanctions against North Korean currency counterfeiting further clouded the atmosphere, and direct contacts ground to a halt.

China's failure

The North Korean nuclear crisis is also a failure of China's bid for regional, if not global leadership. North Korea is an ally of China, a relationship that goes back more than half a century to the Korean War, when Chinese "volunteers" poured across the border to prevent an American victory. Their relationship has become more difficult since China embarked on market reforms while North Korea clung to its peculiar brand of Stalinism.

China has been torn between its loyalty to Pyongyang, its desire to maintain a stable balance of power in the region and its fear that the North's nuclear ambitions could provoke conflict on its borders. By becoming host for the six-party talks, Beijing stepped into an unusual leadership role.

The Bush administration was eager to move the burden of the North Korean problem onto the Chinese. Some administration hard-liners argued that China had the power to trigger the collapse of Kim Jung Il's regime by cutting off energy and food supplies.

Time and again, Beijing dragged the North Koreans back to the negotiating table, while also pushing Washington to engage Pyongyang in the talks. But Chinese irritation over American inflexibility has now been trumped by North Korea's defiance. Chinese policy-makers now wonder how they can punish the North without creating chaos, or war.

Failure of engagement

The final failure lies on the doorstep of South Korea's 10-year-long policy of engagement. The "sunshine policy" asserted that the North could be induced to give up its nuclear option by opening up the isolated communist state and promoting the forces of Chinese-style reform.

After a historic summit meeting in 2000, South Korean aid and trade, even tourists, flowed into the North. South Koreans lost their fear of a former foe, seeing it more as an impoverished lost brother than a mortal threat. Tensions with their American allies rose because of a gap in the North's perceived threat. The United States wondered why its troops should continue to defend South Korea.

Now South Koreans must confront the possibility that the North may have used engagement only to buy time.

THE TWO DANGERS

Threat of war

With eyes on Iraq and the Middle East, the Korean Peninsula has been far from the center of American attention. American forces based in South Korea and Japan have been dispatched to Iraq.

Yet the demilitarized zone that separates the two Koreas remains the most militarized frontier on the planet, with hundreds of thousands of well-armed soldiers poised against each other. Clashes along that frontier used to be commonplace and there are signs of a renewal of tensions. The danger of unintended escalation cannot be dismissed.

What might happen if a U.S. naval vessel, moving to inspect a North Korean freighter - as the U.N. resolution may authorize - is fired on or even captured, as the USS Pueblo was in 1968? It is a frightening scenario already worrying some at the Pentagon and the State Department.

Risk of proliferation

More than anything else, American policy-makers fear that North Korea, emboldened by its nuclear success and perhaps desperate for funds amid economic sanctions, might sell its nuclear expertise to Iran and others, including terrorist groups.

For Pyongyang, an alliance with Iran is a logical response to American and global pressure. The North Koreans have sold ballistic missiles to Tehran since the 1980s and rumors of nuclear cooperation persist.

An American effort to interdict the movement of ships and planes to Iran -- with possible U.N. backing - is probable. But the most likely transit is across the long and loosely controlled land border with China. The amount of plutonium needed to make a warhead is the size of a grapefruit and hard to detect - creating yet another nightmare scenario.

THE OPPORTUNITY

In this otherwise bleak landscape, there is an opportunity. For the first time, there is a chance of a consensus among the key players -- China, Japan, South Korea, Russia and the United States. The passage of a U.N. resolution is a small step in that direction. But the real test will come next, as the nations must cooperate to put pressure on North Korea, while coolly navigating the perils of war and making sure to leave open a diplomatic exit.

There is a slim chance of such concerted action, and a limited window for achieving it. Not everyone sees the dangers the same way. Signs of rethinking errors of the past are no more evident in Beijing and Seoul than they are in Washington or Tokyo. Ultimately, however, if they are to seize this moment of opportunity, all parties must face up to the fact that the policies of the past have failed.

GWS (Gi-Wook Shin): Dr. Hecker, could you please briefly explain the technical dimensions of what has happened? North Korea is claiming great success, but there are some questions about whether this presumed nuclear test was really successful or meaningful.

SH (Siegried Hecker): At this point, as I understand it, the North Koreans have conducted what they call a nuclear test.

South Korea has said seismic signals appear to indicate a 0.5 kiloton, or sub-kiloton, explosion. From reports I have seen, the Australians and the French believe the blast was about 1 kiloton. Thus, three countries have given assessments on the power of the underground explosion, ranging between 0.5 kilotons and 1 kiloton, or 500 and 1000 tons. This likely indicates a nuclear explosion of a relatively low yield, compared to what one would typically expect. Although the Russian defense minister has apparently commented that the explosion was between 5 and 15 kilotons, I have not heard any other nation estimate in this range.

By comparison, the Nagasaki bomb was approximately 20 kilotons, and the initial tests of the five major nuclear powers were all quite large, on this order. Also, when both India and Pakistan tested multiple devices in 1998, some of these tests were of a substantial yield, at least 20 kilotons. But each country also tested three devices that were said to result in explosions of less than a kiloton. Whether these devices did not work or were experimental in nature is still unknown. So, a test on the order of that conducted by North Korea is not unheard of, but it is apparent that the North Korean device produced an explosion considerably smaller than most countries' first nuclear tests.

Regarding the technical dimensions of this event, I would offer two provisos: first, we must give scientists more time to analyze the seismic signals, and second, we must allow more time for analysis of how those seismic signals translate to the yield of the device. This latter task involves a thorough understanding of relevant geology - scientists make models to predict this, but there is always some uncertainty.

GWS: Given the relatively low yield of the test, is it possible that what North Korea has "tested" is not a nuclear device but very powerful conventional weaponry?

SH: It is most likely that this was indeed a nuclear device. There are two plausible explanations for why this test resulted in a relatively low yield. One possibility is that the North Koreans attempted to test a relatively simple nuclear device that was meant to be large, but it did not work quite right. There are two reasons the test of such a device might not have gone as planned. First, the detonators might not have exploded at exactly the right time or the explosive might not have been of the right quality, thus producing a lower yield. Second, if the timing of the "initiator" (additional neutrons that are introduced) was not quite right, this could also decrease the expected yield of the device.

Another possibility is that North Korea was actually trying to test a smaller, much more sophisticated nuclear device, one with a lot of instrumentation to monitor implosion. North Korea could have learned a great deal from such a test, but I would be surprised if the country had really designed the device to be that small.

GWS: This test marks the failure of the disparate policy approaches of South Korea and the United States - neither nation was successful in arresting DPRK nuclear development. But just how advanced North Korea's nuclear program is remains unclear. In the Korean media, there has been debate over whether North Korea's nuclear test was a success or a failure. What do you think?

SH: I would not say that the test failed. It is simply too early to judge, and we do not know exactly what North Korea had hoped to achieve. If North Korea wanted to use this test as a demonstration, then perhaps it was not very successful. It may be the case that the test did not work as well as anticipated if the device in question was a simple nuclear device. If North Korea was testing an advanced designed that was very well instrumented and monitored, it may have learned a great deal from this test.

It is important to wait to see an accurate yield for this test and then to look at the range of possibilities for why it might have been executed. From a scientific perspective, it is important not to overreact and not to go beyond what is actually known.

GWS: You said previously that when India and Pakistan tested nuclear devices in 1998, they both set off multiple explosions. Is it correct that North Korea has set off a single explosion?

SH: From what we have learned so far, it appears that North Korea has tested one device. This is what the North Koreans announced they would do. Scientists will have to carefully analyze the seismic signals to be sure, however, as for example, when India tested, it set off two devices simultaneously. We have not yet seen all the seismic evidence.

GWS: If North Korea were to use such a "low yield" device as a weapon in a major metropolis like Seoul, what kind of impact would it have?

SH: A 1 kiloton bomb in a major metropolis, though a relatively "low-yield" nuclear device, would still be devastating and catastrophic. Many thousands would experience instant death, and due to radioactivity, there would also be many delayed deaths. A device of this size would not wipe out the entire city, as was largely the case in Hiroshima and Nagasaki, but it would cause major, significant damage.

GWS: Based on the scale of the explosion, was this device something that even terrorists could assemble?

SH: One kiloton in terrorist hands would indeed be catastrophic. I am very concerned that North Korea's nuclear material might fall into terrorist hands.

GWS: The possible marriage of this demonstrated nuclear capability and North Korean missiles is extremely dangerous. With reference to the North's nuclear and missile capabilities, is testing useful for making smaller nuclear devices - devices small enough to be placed on a missile?

SH: If North Korea is intent on making a nuclear warhead, this test could be a step in that direction. Making smaller nuclear devices by nature means making more complex nuclear devices. For much of the Cold War, this was a major goal for both the Soviets and the Americans. For North Korea, at this point we cannot say that the test was successful in terms of this aim of miniaturization, though again, North Korean scientists may have learned a lot in this regard. It is extremely difficult to say how soon North Korea could achieve miniaturization with the limited information we have about this test.

Miniaturization is a very big step, and it cannot be accomplished without nuclear testing. This could have been one of the most important reasons that North Korea undertook this test. It must be noted that their missiles are the other part of this equation, and there is not great confidence in the reliability of these missiles, especially those that performed poorly during the July test.

GWS: North Korea has certainly made a political statement with its nuclear test, but from a technical perspective, do you expect additional testing? What is your assessment of North Korea's technical capabilities, in light of your recent visits to the nation?

SH: At this point, North Korea could want another test for two technical reasons. First, if this was a simple device, they will want to fix the problem and demonstrate an explosion of a higher yield. If this was a more advanced design, they may have learned a lot but would still desire another test in order to gain an appropriate level of confidence in the device.

In January 2004, I visited the Yongbyon nuclear reactor and in August 2005, I visited Pyongyang. On the basis of those visits, I would estimate that North Korea has enough plutonium for 6 to 8 nuclear devices, though there is some degree of uncertainty in that estimate. Overall, I estimate the North has 40-50 kilograms of weapons-grade plutonium, and generally 6-8 kilograms are required for each weapon. I also estimate that North Korea could gain one additional weapon per year, given the current rate of reprocessing.

In terms of skilled people and facilities, North Korea has very good capabilities, up to the point of and including reprocessing plutonium. However, to go from reprocessing plutonium to building the device itself takes a whole new set of engineering and physics skills.

GWS: Given North Korea's limited amount of weapons-grade material, its government would presumably want to conserve as much as possible, right?

SH: Yes, and this is probably one of the reasons North Korea did not set off multiple explosions like India and Pakistan did. North Korea has very limited material, and therefore it will want to be judicious. With this conservation imperative, North Korea will want to fully assess what has been learned from this first test before it attempts a second test.

GWS: From a technical perspective, is it difficult to say how long it may be until North Korea conducts a second test?

SH: Yes, it is very difficult to say, because it depends on factors related to this test about which we are still uncertain. If North Korea was satisfied with this test and all preparations have already been made, a second test could take place within a few days. Yet if the findings from this test surprised North Korea, the device may have to be rebuilt, and that could take weeks or months. One thing we know for sure is that they do not have a lot of weapons-grade material, and they will have to carefully judge how to use it.

GWS: You have said that a major danger from the North Korean nuclear program is the possibility of plutonium transfer. How serious is this possibility? Are you also concerned about transfer of nuclear technology?

SH: Well, a test does mean that there is now less material that could possibly be transferred.

I feel strongly that the principal danger from the North Korean program is the plutonium itself, and the possibility it would find its way to a third party, perhaps into terrorist hands or into the hands of other nations. The reason I believe this is the biggest danger is that North Korea could be restrained by its neighbors from ever actually using a nuclear device, but a third party, especially a non-state actor, may not be "restrainable."

The nuclear test will not have an impact on how marketable the plutonium is. Yet, for the export of nuclear technical know-how, a successful test could make a big difference in the appeal of North Korean technology, especially to a nation like Iran.

GWS: The current nuclear crisis erupted in October 2002, when U.S. officials confronted North Korea about its possession of a uranium enrichment, or HEU, program. North Korea has thus far denied having such a program. I understand this type of program is much more difficult to detect. Would a uranium-based device require testing?

SH: North Korea has stated that it does not have an HEU program. My own opinion is they have some type of enrichment program, owing to Pakistani President Musharraf's statements that his nation provided Pyongyang with some of the required technology and equipment. We simply do not know how far North Korea has progressed in this program.

The HEU program is very difficult to detect - there are fewer signatures than for a nuclear reactor and this type of program is easier to conceal, given the smaller size of the facilities required. However, if we assume statements made by A.Q. Khan and President Musharraf are accurate, it may be some time before North Korea can produce significant quantities of HEU.

Once North Korea has accomplished this, a uranium bomb will be easier to make, and North Korean scientists will have more confidence in this type of device without testing.

GWS: All indications are that North Korea will be further isolated after this test. Will this increased isolation impact the country's continued nuclear development?

SH: At this point, from what I saw at Yongbyon, current North Korean operations do not depend on external help or supplies. Thus, isolation makes little difference in this regard. For the uranium program, technical isolation would probably cause a slowdown, because North Korea would benefit from additional technical purchases from the outside world. But the uranium program does not appear to be a centerpiece of North Korea's nuclear efforts.

GWS: After this nuclear test, is the situation more dangerous?

SH: I believe the major threat came around 2003 when North Korea reprocessed a major amount of plutonium, thus crossing the threshold to become a major threat. I have always taken the North Korean threat very seriously, and I believe all the governments and peoples involved should take it very seriously as well. First and foremost, the imperative should be to make sure that nuclear materials stay in North Korea and are not transferred to third parties.

Transcript prepared by Kristin Burke, Shorenstein APARC Research Associate