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No, North Korea did not just test an Iranian nuke.

When I last traveled to Seoul, I took in a ballgame. (I am now a fierce partisan of the Doosan Bears.) I headed to the ballpark, anticipating the perfect marriage of Korean and American culture: kimchi dogs!

As it turns out, South Koreans eat fried chicken at baseball games. Who knew? For reasons I cannot fathom, it has never occurred to anyone to smother a hot dog in spicy kimchi, despite the fact that this is fusion cuisine's answer to peanut butter and jelly. The moral of this little tale is that just because two things ought to go great together, the real world sometimes disappoints.

Which brings us to nuclear cooperation between North Korea and Iran. There have been any number of stories in recent days detailing the allegedly close and continuing cooperation between nuclear weaponeers in both countries. A casual reader perusing the Sunday Times, Jerusalem Post, Kyodo News, and Chosun Ilbo might very well conclude that North Korea's nuclear test was as good as an Iranian one. "Why Iran already has the bomb," was the provocative title of an article in Tablet.

But, like kimchi dogs, it's an obvious idea that doesn't seem to have a basis in fact.

Many of the people pushing the "Iranian test" hypothesis are simply trying to hijack a Northeast Asian crisis for their own preferred policy in the Middle East, which usually involves bombing the crap out of Iran. Others are probably just fascinated by the idea of an international rogues gallery of scientists holed up in a fortress of doom, testing nuclear weapons. (Imagine Mohsen Fakhrizadeh asking Dr. No how he lost his hands, with Ri Je-son rolling his eyes at having to hear that story one more time.)

Few of these authors, however, seem to have thought very carefully about either the status of Iran's nuclear program or the purpose of testing nuclear weapons in general. A careful consideration of both, however, helps illustrate why the reality is probably a lot less exciting than the headlines. There probably is some cooperation, but not of the sort that alters the fundamental policy problem with regard to Iran.

Let's start with the allegations.

The Sunday Times, citing the usual "Western intelligence sources," reported that Mohsen Fakhrizadeh, generally believed to be the head of Iran's shuttered weaponization program, visited Pyongyang, possibly before attending the DPRK's nuclear test. The Jerusalem Post picked up that story, quoting an Israeli academic stating that "The Iranians didn't carry out a nuclear test in Iran, but they may have done so in North Korea." Debka, on the other hand, expressed doubt that Fakhrizadeh would leave the safety of Iran, given the desire of certain intelligence services to see his brains splattered across his dashboard. Kyodo News, citing a "Western diplomatic source" reported that Iran paid tens of millions of dollars to have Iranian scientists observe the test. Chosun Ilbo picked up that story.

Iran and North Korea do, of course, do bad things together. The North Koreans and Iranians were both clients of Pakistani nuclear scientist A.Q. Khan.

Iran and North Korea also have a well-documented cooperation on ballistic missiles. At least one account has the early contacts between North Korea and the Khan network arising from North Korean and Pakistani technicians working on the Iranian missile program during the Iran-Iraq War. The U.S. intelligence community's most recent 721 report -- the unclassified summary of WMD proliferation it periodically sends Congress -- clearly states that North Korea's relationship with Iran "remains strong."

One can clearly see this connection in the missiles themselves. Iran's Shahab-3 is a Nodong clone. Iran's Simorgh appears to be similar to the first stage of North Korea's Unha rocket. The third stage of North Korea's Unha rocket appears to be based on the second stage of an Iranian rocket called the Safir, which is in turn based on vernier engines from a Soviet missile called the SS-N-6 that North Korea appears to have exported to Iran.

Recent allegations of cooperation have some basis in fact. In September, Iran's science and higher education minister signed a memorandum of understanding with the North Korean foreign minister on scientific and technical cooperation. The MOU was followed by a Kyodo News report that Iran had agreed to permanently station missile engineers from Shahid Hemmat Industries in North Korea. The latter claim is plausible but not corroborated. Some observers have pointed to similarities in the test stands at the Shahid Hemmat complex and the North Korean launch site at Tonghae -- a similarity I noted at the time. All test stands look more or less alike, as evidenced by images from the United States. Given the close cooperation between the two missile programs, the idea of a more-or-less continuous presence doesn't seem far-fetched.

The evidence, however, dries up on the subject of nuclear cooperation.

The idea is not crazy. Both Iran and North Korea were clients of the Khan network. North Korea swapped Nodong missiles to Pakistan for help with centrifuges and sold a reactor to Syria, so we know Pyongyang likes money. But there are also some important differences in their centrifuge programs: The Iranians are developing their own evolution of the P1 centrifuge using a carbon fiber material; the North Koreans claim to use some sort of maraging steel. Despite these differences, the pair might share an interest in developing a warhead small enough to place on a missile.

As for actual evidence? It is pretty thin. As I noted at the time Iran and North Korea signed the MOU, North Korea's state-run media outlet, KCNA, released the list of attendees. The fact that the heads of the Defense Ministry and the Atomic Energy Organization of Iran attended caught my attention -- but it is hard to say more than that. One Iranian defector -- and we ought to treat such sources with considerable skepticism -- has asserted that North Korean specialists visited Iran to assist in the "nuclear program," although he did not make clear in what capacity or how he even knew their function.

Perhaps the most reliable report comes from Paul-Anton Krüger in the Süddeutsche Zeitung. "Western intelligence sources" told Krüger that North Korea transferred a U.S. computer code that models radiation transport, MCNPX, to Iran.

And that's about it. Is there cooperation within the centrifuge programs? Might it extend to warheads? Maybe. Hard evidence is in short supply. Japanese and South Korean officials have repeatedly asked their U.S. counterparts whether nuclear cooperation exists between North Korea and Iran. You can read the private remarks behind closed doors thanks to Wikileaks: In December 2007, Japanese Assistant Chief Cabinet Secretary Hiroyasu Ando asked acting-Undersecretary of State for Arms Control and International Security John Rood about cooperation between North Korea and Iran on nuclear weapons: "Acting U/S Rood indicated no evidence had been found of exchanges on nuclear or associated technology between the two countries despite longstanding and ongoing cooperation on missile development."

The MCNPX episode might qualify that statement a bit, but we're still just guessing.

It is actually kind of interesting to imagine what might limit cooperation between Iran and North Korea. One factor may simply be North Korean enthusiasm for secrecy. Leslie Groves has nothing on the North Koreans when it comes to keeping tabs on nuclear scientists. When Burmese dissidents obtained a report detailing a trip by military officials to North Korea, Pyongyang reportedly leaned on the Burmese junta to execute the leakers. And A.Q. Khan -- who can be counted on to save his own skin -- seems to have gone to extraordinary lengths to protect his North Korean contacts, even while ratting out the Libyans and Iranians. That ought to tell you something. A cursory glance at the IAEA annex on "possible military dimensions" of Iran's nuclear program, on the other hand, suggests the Iranians aren't much on security. I imagine the North Koreans are not terribly eager to stick any Iranian thumbdrives in their computer systems. And if North Korea did transfer the MCNPX code to Iran, I am certain that the cadres in Pyongyang did not enjoy reading about it in the morning paper. The Iranians may share "the common idea of anti-imperialism and anti-U.S. struggle," but they are still foreigners.

Then there is the question of whether cooperation would, in the grand scheme of things, make much of a difference. Indeed, if we think about Iran's nuclear program and the role that nuclear testing might play, showing up at a North Korean nuclear test is probably more about sticking it to the man than anything else. At the end of the day, a North Korean test is simply not the same thing as an Iranian test.

Let's take another look at the Iranian nuclear program. The view of the U.S. intelligence community, which I continue to think is the most reasonable view, is that Iran pursued a covert weapons program before pausing it under international pressure in 2003. Iran could restart the program at any time, which creates an interesting policy problem: An attack on Iran might destroy some capabilities and kill some scientists, but it would result in Iran pushing "play" on a bomb program. That's not a sensible thing to do as long as we have confidence the program remains paused.

Some people are claiming that a North Korean test is also an Iranian test for the same reason they claimed Iran had reorganized its Physics Research Center -- to assert that Iran has restarted its weapons program and that we must now move toward military action. In both cases, however, Iran is simply maintaining its nuclear weapon option. That's not a very happy thought, but it would be Iran's exercise of the nuclear option that sends us to the mattresses.

Iran almost certainly knows how to build a miniaturized nuclear device. China provided Pakistan with information about a nuclear weapon small enough to fit on a DF-2 missile, which the Pakistanis further miniaturized and tested in 1998. Authorities breaking up the Khan network found copies of Pakistani designs in Libya and Switzerland. As customers of the Khan network, Iran and North Korea almost certainly have access to this information. (Iran has already provided the IAEA with one weaponization-related document supplied through the Khan network.) Iran also has access to former Soviet nuclear weapons scientists, including Vyacheslav Danilenko, who seems to have described a rather slim detonator arrangement that is useful for a variety of industrial applications involving shock implosion, such as producing nanodiamonds and digging canals.

There is no fundamental secret to building a miniaturized device. Most of the important innovations are well documented in the public literature. I am sure there are Farsi translations of the Los Alamos Primer and the Smyth Report, Chuck Hansen's U.S. Nuclear Weapons: The Secret History, John McPhee's Curve of Binding Energy, and one or two other choice publications on bookshelves in leafy suburbs of Tehran like Lavizan. North Korea doesn't need to put Mohsen Fakhrizadeh up at the Koryo to explain levitated pits. We don't know the status of Iran's design program at the time the program was paused in 2003, but they are surely familiar with the major approaches to building missile-deliverable warheads.

That brings us to the purpose of testing. Why test at all?

Much of the U.S. testing program was about exploring, understanding, and validating design approaches. The United States explored all sorts of interesting design approaches, including a few dead ends. The advantage to Iran and North Korea is that the United States has already demonstrated through testing that certain approaches work in principle. Moreover, they probably have access to actual designs that have been validated in tests.

The problem for Iran and North Korea is how to execute those approaches in practice. That presents some interesting engineering challenges, but hardly insurmountable ones. In 2002, the National Academies argued that states like Iran and North Korea could build miniaturized nuclear devices, though these weapons would not be reliable without testing. "A single full yield test," they explained, "would validate both the legitimacy of a blueprint and success in reproducing the object." North Korea learned about the importance of conducting a test the hard way -- with a disappointing 2006 test of what was probably a miniaturized warhead.

One may get a sense of the purpose of testing from the nuclear cooperation between the United States and the United Kingdom. The United States provided significant support to the U.K. nuclear weapons program -- U.K. warheads are "Anglicized" versions of U.S. ones like the W76. There are some differences, of course, between U.S. warheads and their British cousins. Brits will tell you that they have more stringent safety requirements when it comes to high explosives and the like, while Americans will tell you that British manufacturing gave the world the Austin Allegro. Either way, everyone agreed that Britain needed nuclear tests to confirm they had successfully reproduced U.S. warheads.

After 1962, the United Kingdom conducted its nuclear weapons tests at the Nevada Test Site in the United States. Joint tests involved a U.K. device, diagnostic hardware, and British personnel. (The United States provided other equipment, leading to some interesting interface issues, and the test was conducted jointly under a U.S. test director, who had the final say, and a British trial superintendent.) Although the United States provided an off-the-shelf design with an exquisite test pedigree, the United Kingdom still needed to ensure that changes introduced in manufacturing the device did not have adverse effects. Simply attending U.S. tests as a VIP guest might be enjoyable, but it does not substitute for testing one of your own devices.

Now consider the case of Iran. Iran probably has plenty of information on previously tested warheads from China, Pakistan, and the former Soviet Union, as well as North Korea. The real question is whether they can successfully reproduce the object. If Iran wishes to build a miniaturized nuclear warhead, Tehran ought to want to test it. So, unless the device test in North Korean was Iranian manufactured, the question remains.

Now, of course, the Iranians might still learn other things from a North Korean nuclear test. There are also important lessons for digging and instrumenting the test tunnel, particularly with regard to containing the explosions. Someone from Kimia Madan might enjoy hanging out at Chongjin University of Metal Mining. But unless the Iranians manufacture their own device and detonate it in North Korea, the Iranians still do not know if they have a missile-deliverable weapon. Now of course, the Iranians might be overconfident or simply not care that future warheads are unreliable. But then, what's the point of attending the North Korean test other than to be churlish?

Iran's interest in North Korea's nuclear program is something worth watching, but VIP visits to test sites simply do not alter the current policy choices regarding Iran. Fakhrizadeh's nuclear program is still paused, even if he got a ringside seat for the juche bomb. I wrote last year regarding allegations of yet another reorganization of his tawdry little empire: "Oh, this is interesting all right, and worth considering, but hardly the sort of thing one puts in a PowerPoint to U.N. Security Council. Um, moving on."

ATTA KENARE/AFP/GettyImages

National Security

North Korea's Big Bang

Did Pyongyang just take a big step toward an arsenal of nuclear-tipped missiles?

When the email notification of a shallow 4.9 tremor near the North Korean nuclear test site landed in my inbox, courtesy of the United States Geological Survey, I went to Twitter:

It go boom.

The magnitude of the explosion, now revised to 5.1, is significantly larger than North Korea's previous nuclear tests in 2006 (4.3) and 2009 (4.7). Seismic scales are logarithmic, so 5.1 is much larger. The corresponding size of the explosion or "yield" is several kilotons, or thousands of tons of TNT -- although we should treat all yield estimates at this point as rough approximations. (I've posted a long discussion on the perils of estimating yield based on the simple seismic data at ArmsControlWonk.com.)

The point is, this one is bigger. Although it's not nearly so big as the modern thermonuclear weapons in the U.S. arsenal -- which range from hundreds of kilotons to a megaton -- you really wouldn't want this dropped in your neighborhood.

More importantly, however, North Korea has announced that the device was a "miniaturized and lighter nuclear device with greater explosive force than previously." What this boils down to is a North Korean claim that this nuclear weapon will fit on a missile like the Nodong. Or maybe even the KN-08, which the North Koreans say over and over is intended for us. Like a valentine.

The question is, do we believe them? And if we do believe them, does it mean we have to think about this problem differently?

There are basically two approaches to these questions, which arise from differing interpretations of the rather small yields of the first two North Korean nuclear tests -- a few hundred tons in 2006 and about two kilotons in 2009.

One view is to insist the North Koreans prove they are not terrible at building nuclear weapons. Here, I need to introduce you to a term of art: "simple fission device." This is a bulky nuclear weapon of the sort that the United States dropped on Nagasaki. That bomb weighed 4,000 kilograms (over four tons!) and contained six kilograms (about 13 pounds) of plutonium. The yield was about 20 kilotons. It was affectionately called "The Gadget," which is funny in precisely the opposite way that it's amusing to name a Chihuahua "Bruiser." The massive Gadget would have been far too large to be delivered by a missile, if the United States had any at the time. No country has ever built a simple fission device and discovered it did not work. Hence, "simple," as in anyone can do it.

Until the North Koreans, that is. In this telling, the North Korean nuclear program, like the North Korean missile program, required multiple tries to achieve success: in this case, building a Gadget-sized simple fission device. The third time was a charm -- but North Korea is still stuck with 1945 technology, wondering whether the damn thing will fit in the bomb bay.

The second view, to which I am inclined, is that we ought to take the North Koreans at their word. This view arises from the judgment that North Korea's disappointing yields in 2006 and 2009 are not the result of technical incompetence so much as outsized ambition. The North Koreans tried to skip some steps and go directly to miniaturized devices.

The United States quickly reduced the mass and dimensions of its nuclear weapons, largely by making the process of implosion more efficient. When I visited the historical collection at the Atomic Weapons Establishment in Aldermaston, England, I was surprised to see a rather explicit description of the use of air pockets among the lenses to improve the efficiency of explosions. There are other tricks, too, like suspending or "levitating" the plutonium pit. (The physicist Ted Taylor elegantly illustrated the idea by asking, "When you hammer a nail, what do you do? Do you put the hammer on the nail and push?") The result was a steady reduction in size, without the loss of explosive power. One of the first miniaturized U.S. fission weapons, the Mark 7, weighed just 750 kilograms and used considerably less plutonium than the Gadget.

It's no coincidence that the U.S. intelligence community, in the late 1990s, estimated that 650-750 kilograms was probably the best that North Korea could do without testing. The Mark 7 is used as a proxy for what a new nuclear state might attempt to build. China gave Pakistan a roughly comparable design, which Pakistan may have further shrunk, as well as sold to Libya and god knows who else. There are reports that Iran had access to a still more compact Soviet design.

The general view, however, is that miniaturized weapons are unreliable without testing. The question is whether the North Koreans attempted immediately to build a Mark 7-sized device, perhaps because they placed too much confidence in data acquired from the Soviet Union or Pakistan, or because they were just plain drunk on juche.

There is some evidence for this view, although it is admittedly circumstantial. In 2003, David Sanger reported that the United States noticed the North Koreans doing an unusual amount of testing with high explosives. The typical path toward shrinking nuclear weapons involves reducing the amount of explosives needed to compress a sphere of either plutonium or highly enriched uranium. The intelligence community, according to Sanger, concluded that North Korea was attempting to do better than a simple fission device, trying "to make nuclear warheads small enough to fit atop the country's growing arsenal of missiles."

Then, in 2005, a certain North Korean official defected. "Kim Il-do" claimed to have worked for the Second Economic Committee of the National Defense Commission, which oversees North Korea's nuclear and missile programs. Kim had some interesting things to say about North Korea's nuclear weapons program. Here is a translation from the Korean article by my colleague, Hanah Rhee:

Mr. Kim, during an interview with [South Korea's] National Intelligence Service, said that North Korea had manufactured a one-ton nuclear warhead with four kg of plutonium. He also said "North Korean scientists reported to Kim Jong-il that the weapon is functional, however, they have doubts about the level of performance that they manufactured." Mr. Kim said, "North Korea is not confident whether their large-sized nuclear weapons can actually work in practice which is why they are developing a smaller 500 kg version." 

At the time, I was inclined to doubt the guy. That's not how the United States, or anyone else, did it. And for good reason -- if North Korea were to test such a weapon, the result would probably be a humiliating failure.

Then North Korea tested a humiliating failure.

North Korea told China to expect a four-kiloton yield. That's broadly consistent with what one might expect from a device with only four kilograms of plutonium. The actual result was a few hundred tons' worth of yield. Not something you'd want dropped on your neighborhood, to be sure, but also not something you'd be eager to explain to the Dear Leader. Suddenly, at least to me, Kim Il-do didn't seem so crazy.

If you believe this second theory of North Korea's strategic development, then North Korea isn't incompetently following the U.S. or Soviet nuclear weapons development path. With fewer tests, North Korea is trying to move more quickly to larger, deliverable warheads based on the experience of others. Although I suspect I'm in the minority, I still believe that the North Koreans' ultimate goal is a stockpile of missile-delivered thermonuclear weapons. Broadly speaking, I suspect this test is a step toward that end. There are many technical details that we don't know at the moment -- and may never know. We don't know yet whether the device used plutonium, highly enriched uranium, or both, and we might never know. We also don't know how North Korea made a bigger bang this time -- whether the progressively larger explosions represent improvements in the existing approach or changes in the entire design philosophy.

But we should treat North Korea's own statements about miniaturization seriously.

Not taking the North Koreans seriously compromises our ability to formulate a realistic approach to managing the problem. We have a tendency to see North Korea's nuclear program as a vaguely ridiculous enterprise that exists largely to extort the United States. This view underestimates North Korea's ambition with regard to its nuclear weapons program and the importance that the leadership in Pyongyang places on it. Kim Jong Un is not going to take the route Muammar Qaddafi did and give up his nuclear and missile programs -- they are much too central to his regime's ideology. (This is to say nothing of the terrible precedent that Qaddafi's overthrow set. After learning about the last few minutes of his life, I sat gingerly for a week.)

If you want to know how the North Koreans think about their nuclear weapons, watch these subtitled clips from the North Korean propaganda film, The Country I Saw. The complete, verifiable, and irreversible disarmament of North Korea, as it were, will require a comprehensive settlement of the questions arising from the Korean War. Let's not hold our breath.

Being realistic about the dim prospects for disarmament should include an appreciation that things can get worse. A lot of pundits and politicos treat nuclear weapons as an either/or proposition. You have ‘em, or you don't. A classic example of this sort thinking was a comment by Colin Powell, who argued in 2002 that the collapse of the 1994 Agreed Framework, which had frozen North Korea's nuclear program, was harmless because the North already had nuclear weapons. "What are they going to do with another two or three nuclear weapons?" he asked on one of the Sunday talk shows. (He seems to have done five that day, giving variations on theme of "so what?") A small stockpile of reliable warheads small enough to ride a missile is clearly worse than a single one-ton device that doesn't work. And, if we do nothing, whatever stockpile North Korea has in 10 years' time could easily be worse than its current arsenal.

We ought to be careful about encouraging the North Koreans to prove it to us. I understand, and support, the Obama administration's insistence on the talking point that we do not accept North Korea as having the formal status of a nuclear state. But making it clear that Pyongyang's isolation cannot end with a nuclear-armed North Korea does not require insisting that it demonstrate each measure of capability. In the mid-1960s, the Chinese made some interesting choices about how to ensure the neighbors took them seriously. One was to mount a miniaturized nuclear weapon on a DF-2 missile and fire it 1,200 km across China. That was the fourth Chinese nuclear test. (The design from that test, which used highly enriched uranium, was the one that later showed up in Pakistan and Libya. One presumes more copies are floating around.) The North Koreans seem unwilling to test in the atmosphere for a variety of reasons, so I suspect this is an unlikely precedent. But it is worth keeping in mind that things could be much, much worse. There is value to simply managing a problem, especially when there are no better options.

We can all recite a list of options to manage this particular headache. Prominent among them: partial agreements to freeze fissile-material production, nuclear testing, and rocket launches. These steps will not eliminate North Korea's capabilities, but now it's my turn: So what? What better plan can you imagine? I think back to former diplomat Bob Gallucci's frustration with critics of the much-maligned 1994 freeze, admittedly an unsatisfying approach:

"When I came back with the Agreed Framework deal and tried to sell it," he said, "[Many people] hated the idea of trying to solve this problem with a negotiation.

"And I said, ‘What's your -- pardon me -- your fucking plan, then, if you don't like this?'

‘We don't like --'

"I said, ‘Don't tell me what you don't like! Tell me how you're going to stop the North Korean nuclear program.'

‘But we wouldn't do it this way --'

‘Stop! What are you going to do?'

"I could never get a goddamn answer."

That's because there isn't a goddamn answer. There is no better plan that stops the North Korean nuclear program. The North Koreans will probably cheat and we will be rewarding bad behavior. So f'ing what? Unless, of course, you have a better idea. Then, by all means, be my guest.

Chung Sung-Jun/Getty Images