Possible North Korean nuclear test

[phongn]

SEOUL – North Korea said it conducted its second test of a nuclear device on Monday morning, making good on a warning it issued in the wake of a long-range missile test in early April.

The country's state media announced the test at noon local time, about two hours after defense monitors in South Korea detected an "artificial earthquake" in the same place where North Korea conducted its first nuclear test in October 2006. North Korea said the explosion was more powerful than occurred in the first test.

A seismic reading of 4.5 on the Richter scale was detected by the South Korean monitors.

North Korea on April 29 issued a statement saying that it would conduct more tests of nuclear devices and missile systems. The statement came after the United Nations Security Council issued a statement criticizing the country's April 5 test of missile-like rocket.

North Korea has used the development of nuclear weapons to build its own military strength, drive a weapons-sale program and as a diplomatic tool for extracting economic aid and security concessions from other countries.

USGS has some data on the seismic event.

[KlavoHunter]

I hope Kim Jong-Il has the good grace to die, so that North Korea ends up with a hopefully more sane successor, before he does something utterly foolish with the nukes that he now possibly has.

[Questor]

If USGS is right, then they screwed it up again. According to the USGS, a 4.7 is only the equivalent of between 6.3E10 and 2E12 J.

[Sea Skimmer]

I hope Kim Jong-Il has the good grace to die, so that North Korea ends up with a hopefully more sane successor, before he does something utterly foolish with the nukes that he now possibly has.

We can hope that a change would be for the better… but I just don’t think that is very realistic. Kim is primarily a figurehead, and even if he has a firm successor picked a major power struggle is inevitable within the ranks of the generals, admirals, and top party officials who sort of rule the place by committee. Without even a figurehead to rally around North Korea may well just become even more incomprehensible in its actions and motivations. Things won’t get better until the Army will no longer take orders to shoot peasants. Supposedly that actually did happen during the 1990s famine, but the Norks executed hundreds of officers and then implemented a comprehensive policy to ensure that a sufficient cadre of the army is kept fed to maintain order.

[Dargos]

N. Korea confirms they did tested a nuke. link

SEOUL, South Korea (CNN) -- North Korea has conducted its second nuclear test, the country's state news agency announced Monday.


This screen grab from North Korean television on April 9 shows leader Kim Jong Il in Pyongyang.

The confirmation came little more than an hour after the U.S. Geological Survey reported a magnitude 4.7 seismic disturbance at the site of North Korea's first nuclear test in October 2006. The North Korea's Korean Central News Agency said Monday's test was conducted "as part of the measures to bolster up its nuclear deterrent for self-defense in every way."

In Seoul, South Korean President Lee Myung-Bak's office said the country was investigating the reported test and would hold an emergency meeting of its national security council.

And in Tokyo, Prime Minister Taro Aso's office said it has set up a special task force to look into the test and how to respond.

There was no immediate response from Washington or Beijing. Watch how the test may have taken world by surprise »

"The current nuclear test was safely conducted on a new higher level in terms of its explosive power and technology of its control and the results of the test helped satisfactorily settle the scientific and technological problems arising in further increasing the power of nuclear weapons and steadily developing nuclear technology," KCNA announced.

There was no immediate information on the yield of the weapon used. But the first North Korean test produced, according to U.S. intelligence estimates, an explosion equal to less than 1,000 tons of TNT -- a fraction of the size of the bombs the United States dropped on Japan at the end of World War II. Watch South Korea's initial reaction to North Korea's nuclear test »

The test, which North Korea had threatened after the U.N. Security Council criticized Pyongyang's April 5 test of a long-range rocket, was "faster than expected," said Jim Walsh, an international security analyst at the Massachusetts Institute of Technology.

The questions raised by the test are less military and more political, he added.

"We know so little about this country," Walsh told CNN. "We don't have good relations with them, they're going through a leadership transition and on top of that, they test a nuclear weapon. So the problem with this is we're not going to have military action, but it's all the uncertainty and political consequences."

The test comes two days after former South Korean President Roh Moo-Hyun, who'd sought improved relations with North Korea during his 2003-2008 tenure, committed suicide. Just before he left the presidency, Roh became the first South Korean leader to cross the demilitarized zone and meet with North Korean leader Kim Jong Il. Watch how Roh's legacy may be remembered »

Roh's successor, Lee, takes a harder line on the north and has so far not continued Roh's efforts.

The test also comes less than three weeks after the United States announced a new diplomatic effort to restart the stalled North Korean nuclear talks. The Obama administration's designated point person on North Korea, Stephen Bosworth, visited the region for talks with China, South Korea, Japan and Russia -- the other participants in the six-party talks.

In July 2008 negotiators reached agreement with Pyongyang on a timetable for North Korea to resume disabling its nuclear facilities. But the reclusive communist state balked at the deal, demanding the United States first take it off its list of state sponsors of terrorism.

The Bush administration lifted that designation in October, but plans to push for an agreement allowing the other parties to check whether Pyongyang has revealed all of its nuclear secrets stalled.

In June 2008, North Korea acknowledged producing roughly 40 kilograms of enriched plutonium -- enough for about seven nuclear bombs.


But North Korea remains "years and years" away from having a weapon it can put atop a long-range missile like those in the United States, Chinese or Russian arsenals, said Walsh, the international security analyst.

"Nothing good" can come from Monday's test, he said, "but it doesn't mean they're going to have a real working nuclear weapon tomorrow or next year."

[The Duchess of Zeon]

The yield of the device in question was, based on the reported richter scale of the event, between 400 - 600 tons of TNT equivalent, probably closer to the upper end of that range. To give you an idea of comparison, 400 tons of TNT equivalent was the Davy Crockett nuclear recoilless rifle shell's yield, or the yield of the nuclear-tipped air to air rockets and missiles of the late 50's / early 60's. It was also a dial-a-yield option on some other nuclear devices. There is no guarantee that the low yield was the result of a fizzle; it could instead result from efforts at miniaturizing nuclear devices enough to fit on North Korea's existing missiles. Even if the detonation was only partial, however, don't laugh--600 tons of TNT concentrated in one place could have easily brought down the Twin Towers on 9/11 with that kind of blast pattern and intensity, and more to the point, a full-sized nuclear device producing that yield would be insanely dirty.

Little Boy, the Hiroshima bomb, was extremely dirty compared to modern 120kT SLBM nukes, but this device would be so dirty that, in ratio, Little Boy would be as clean in comparison to it, as those modern 120kT nukes are in comparison to Little Boy. Setting it off close to the ground could easily render Manhattan uninhabitable for months of cleanup, for example, in addition to the blast damage, and poison thousands; it would essentially be a tactical nuclear device being used as a bursting charge to spread radiological materials to make the most powerful radiological bomb possible, so even if they haven't been able to get a full nuclear yield, this weapon, unlike the earlier one, could actually right now be effectively used to rip the heart out of Seoul, or poison Tokyo bay and shut it off to international shipping for months. This is, if the weapon is small enough to be delivered, now an actual nuclear combat capability on the part of the North Koreans.

[KlavoHunter]

We can hope that a change would be for the better… but I just don’t think that is very realistic. Kim is primarily a figurehead, and even if he has a firm successor picked a major power struggle is inevitable within the ranks of the generals, admirals, and top party officials who sort of rule the place by committee. Without even a figurehead to rally around North Korea may well just become even more incomprehensible in its actions and motivations. Things won’t get better until the Army will no longer take orders to shoot peasants. Supposedly that actually did happen during the 1990s famine, but the Norks executed hundreds of officers and then implemented a comprehensive policy to ensure that a sufficient cadre of the army is kept fed to maintain order.

Ah, but the sooner, the better. If Kim Jong-Il died tomorrow, their nuclear arsenal would be small to nonexistent, and production is unlikely to continue through the power struggles, unless things get wrapped up quickly and tidily.

Fortunately for that possibility, Kim looks like shit.

[Sea Skimmer]

The yield of the device in question was, based on the reported richter scale of the event, between 400 - 600 tons of TNT equivalent, probably closer to the upper end of that range. To give you an idea of comparison, 400 tons of TNT equivalent was the Davy Crockett nuclear recoilless rifle shell's yield, or the yield of the nuclear-tipped air to air rockets and missiles of the late 50's / early 60's.

Not quite, the normal Crocket warhead and the one we actually tested in the open air was around 20-40 tons, though a later model of warhead for the longer ranged 155mm version of Crocket had a 1,000 ton burst. Genie was 1.5kt, though some of our latter nuclear air to air missile projects like AIM-26 would have had 250 ton warheads which is perhaps what you were thinking of.

In any case checking the calculator, a 600 ton yield would give a 5psi air blast radius of about 600 meters, at which distance initial radiation levels would be over 1000 rems. 20psi radius would be about 225 meters. That means anyone not behind and under major cover may well die over a span of up to 1.2km, and unless you are in a bunker anyone over a 400 meter span is just plain dead. Not bad for a fizzle. Add in chemical warheads going off all around it and making rapid rescue and recovery impossible and tens of thousands would surely die.

[Sky Captain]

I`d think Kim is smart enough to know that using atomic bomb against South Korea or Japan (or any other country) is the quickest way to oblivion for him. So it`s more likely the atomic bomb is going to be used as another political leverage while negotiating with West for aid or something.

[cosmicalstorm]

Would the US military reply with nuclear weapons if the Norks sent them at South Korea or Japan?

[K. A. Pital]

DPRK could be taken out by conventional strikes. In any case, what does Kim have to gain from nuking Korea or Japan? Nothing.

Nuclear weapons for the DPRK are means of deterrent, self-preservation instruments for the regime, and finally a bargaining tool - like for most other nations actually. They're not weapons to be deployed or used.

[Questor]

The russians are claiming it was 10-20KT. Is it possible it was that big from the seismic event?

North Korea declares it conducted nuclear test

By JEAN H. LEE
Associated Press Writer

SEOUL, South Korea (AP) -- North Korea claimed it carried out a powerful underground nuclear test Monday - much larger than one conducted in 2006 - in a major provocation in the escalating international standoff over its rogue nuclear and missile programs.

The country's official Korean Central News Agency said the regime "successfully conducted one more underground nuclear test on May 25 as part of measures to bolster its nuclear deterrent for self-defense."

Russia's Defense Ministry confirmed an atomic explosion at 9:54 a.m. (0054 GMT) in northeastern North Korea, estimating the blast's yield at 10 to 20 kilotons - comparable to the bombs that flattened Hiroshima and Nagasaki.

Hours later, the regime test-fired three short-range, ground-to-air missiles, the Yonhap news agency reported, citing unnamed sources. U.N. Security Council resolutions bar North Korea engaging in any ballistic missile-related activity.

President Barack Obama called the moves "blatant defiance" of the Security Council and a violation of international law that would only further isolate North Korea.

North Korea's claims "are a matter of grave concern to all nations," he said, calling for international action in a statement from Washington. "North Korea's attempts to develop nuclear weapons, as well as its ballistic missile program, constitute a threat to international peace and security."

British Prime Minister Gordon Brown condemned the test as "erroneous, misguided and a danger to the world."

Japanese Prime Minister Taro Aso said the Security Council will meet at 4:30 p.m. Monday in New York (2030 GMT).

"North Korea's nuclear test poses a grave challenge to nuclear nonproliferation and clearly violates U.N. Security Council resolutions," he said in Tokyo. "We are not tolerating this at all."

Even China, North Korea's traditional ally, issued rare criticism of Pyongyang, with the Foreign Ministry saying in a statement posted on its Web site that Beijing was "resolutely opposed" to the test.

North Korea's bold defiance raises the stakes in the standoff over its nuclear program. In the past two months, Pyongyang has launched a rocket despite international calls for restraint; abandoned international nuclear negotiations; restarted its nuclear plants; and warned it would carry out the atomic test as well as long-range missile tests.

The rise in tensions comes amid questions about who will succeed impoverished North Korea's authoritarian leader, 67-year-old Kim Jong Il, who is believed to have suffered a stroke last August. North Korea also has custody of two American journalists - accused of entering the country illegally and engaging in "hostile acts" - who are set to stand trial in Pyongyang on June 4.

"This is a political act more than a military act," said Jim Walsh, an international security expert at the Massachusetts Institute of Technology.

Walsh said domestic factors related to North Korea's political transition were likely the main factor.

Monday's atomic test was conducted about 50 miles (80 kilometers) northwest of the northern city of Kilju, Russian Defense Ministry spokesman Alexander Drobyshevsky said, speaking on state-run Rossiya television.

Kilju, in the northeastern province of North Hamgyong, is where North Korea conducted its first nuclear test in October 2006 in a surprise move that also angered China and drew wide-ranging sanctions from the Security Council.

An emergency siren sounded in the Chinese border city of Yanji, 130 miles (200 kilometers) to the northwest. A receptionist at Yanji's International Hotel said she and several hotel guests felt the ground tremble.

North Korea boasted that Monday's test was conducted "on a new higher level in terms of its explosive power and technology of its control" than in 2006.

Pyongyang is believed to have enough weaponized plutonium for at least a half-dozen atomic bombs. However, experts say scientists have not yet mastered the miniaturization needed to mount a nuclear device onto a long-range missile.

Ten to 20 kilotons would be far more than North Korea managed in 2006. U.S. intelligence officials said the 2006 test measured less than a kiloton; 1 kiloton is equal to the force produced by 1,000 tons of TNT. However, Russia estimated the force of the 2006 blast at 5 to 15 kilotons, far higher than other estimates at the time.

Radiation levels in Russia's Primorye region, which shares a short border with North Korea, were normal Monday several hours after the blast, the state meteorological office said.

In Vladivostok, a city of 500,000 people about 85 miles (140 kilometers) from the Russian-North Korean border, translator Alexei Sergeyev said he wasn't concerned about the test and doesn't fear North Korea.

"Their nuclear program does not have military aims - their only aim is to frighten the U.S. and receive more humanitarian aid as a result," said Sergeyev.

The reported test-firing of short-range missiles took place at the Musudan-ri launchpad on North Korea's northeast coast, some 30 miles (50 kilometers) from the nuclear test site, Yonhap said. Unnamed sources described it as a ground-to-air missile with a range of 80 miles (130 kilometers).

Japan's coast guard said Friday that North Korea warned ships to avoid waters off the coast near the launch site, suggesting Pyongyang was preparing for a missile test. Yonhap also reported brisk activity along the northeast coast last week.

South Korean troops were on high alert but there was no sign North Korean soldiers were massing along the heavily fortified border dividing the two nations, according to an official at the Joint Chiefs of Staff headquarters in Seoul. He spoke on condition of anonymity, citing agency policy.

The two Koreas technically remain at war because their three-year conflict ended in a truce, not a peace treaty, in 1953.

Tensions have been high since conservative President Lee Myung-bak took office in Seoul in February 2008 saying Pyongyang must fulfill its promises to dismantle its nuclear program before it can expect aid.

South Koreans, meanwhile, were grappling with the suicide two days earlier of Lee's liberal predecessor, Roh Moo-hyun, whose death elicited condolences from Kim Jong Il. Kim held a 2007 summit in Pyongyang with Roh, who championed reconciliation with North Korea.

North Korea had agreed in February 2007 to a six-nation pact to begin disabling its main nuclear reactor in exchange for 1 million tons of fuel oil and other concessions. But Pyongyang abruptly halted the process last summer over a dispute with Washington over how to verify its 18,000-page list of past atomic activities.

Talks hosted by Beijing in December failed to resolve the impasse, and North Korea abandoned the six-nation negotiations last month in anger over the U.N. condemnation of its rocket launch.

North Korea claims it launched the rocket to send a satellite into space; South Korea, Japan and other nations saw it as a way to test the technology used to launch an intercontinental ballistic missile, one capable of reaching the U.S.

---

Associated Press writers Kelly Olsen and Jae-soon Chang in Seoul, Pamela Hess in Washington, Steve Gutterman in Moscow and Shino Yuasa in Tokyo contributed to this report.

© 2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. Learn more about our Privacy Policy.

[phongn]

Remember that not all the energy from the event will translate into moving earth.

[CJvR]

10-20kt?
Seems as if they got it somewhat right this time then after the questionable first attempt.

[erik_t]

I'd be very surprised if whatever this weapon is was designed for less than 10kT give or take. Miniaturization of nuclear devices is non-trivial; even if their goal is a (say) 600T device, they'd not go after that until they had made the bigger one work first.

[CJvR]

I doubt the Norks are deliberatly trying for small yield warheads, there would be no point in doing that for them. They want something that can make big dents in Tokyo and Seoul.

[The Duchess of Zeon]

Well, it was described as an underground test, so I had assumed that would leave a very strong correlation between the strength of the earthquake and of the nuclear event; if that's not the case (for example if it wasn't buried that deeply, or I'm neglecting something, which is quite possible), it could reflect a full strength device fairly easily. Didn't we have a similar discrepency between the Russian and American reports of the yield for the first test, too, just that both estimates were of course proportionally much smaller than this?

[Pelranius]

Well, the sources I've read elsewhere suggest a yield of 4 to 8 kilotons, going by the seismic activity.

Arms Control Wonk

Ack, there is a reason I have a rule about blogging before a cup of coffee. In an earlier post, I made a math mistake (actually several, including a data entry error in a spread sheet).

Anyway, here is the data on the North Korean nuclear test, with very simple yield estimates.

The US Geological Survey, NORSAR and the Geophysical Survey of Russian Academy of Sciences all cluster in an Mb range of 4.5-5.0 — about 2-6 kilotons.
Author ID Magnitude Yield (kt)
NAO 11473033 4.5 2
NEIC 11473034 4.7 3
MOS 11473087 5.0 6

International Seismological Center

You’ll want to double check these — I am taking the day off.

I’d love to see what AFTAC says.

Update: The Project for the CTBT has a calculation from Martin Kalinowski:

The U.S. Geological Survey readings indicate a seismic body wave of magnitude of 4.7, which is larger as compared to the value of 4.1±0.1 in 2006. According a preliminary assessment by Martin Kalinowski of the University of Hamburg, this corresponds to an explosive yield of about 3 to 8 kilotons TNT equivalent with a most likely yield of 4 kt. In 2006. The yield of the 2006 test explosion was approximately 0.5 to 0.8 kt TNT equivalent.

http://www.armscontrolwonk.com/

[The Duchess of Zeon]

Alright, so I'm off with that. It's interesting that their final agreed yield for the first device was actually about as high as I'd estimated for this one--at the time, I'd seen a lot of people dismiss it as only a few dozen tons or so, and definitely a fizzle. It seems that one of the reasons for taking the North's nuclear ability seriously is that the ultimate estimates were revised upwards, and here they reflect that. So, it's a real nuclear capability, though 4kT would tend to imply a somewhat smaller than average device, the question being if it's physically smaller, i.e., more capable of being used as a missile warhead.

[Nephtys]

Alright, so I'm off with that. It's interesting that their final agreed yield for the first device was actually about as high as I'd estimated for this one--at the time, I'd seen a lot of people dismiss it as only a few dozen tons or so, and definitely a fizzle. It seems that one of the reasons for taking the North's nuclear ability seriously is that the ultimate estimates were revised upwards, and here they reflect that. So, it's a real nuclear capability, though 4kT would tend to imply a somewhat smaller than average device, the question being if it's physically smaller, i.e., more capable of being used as a missile warhead.

I'm under the impression that smaller, simpler and cheaper warheads would still have larger yields than that. There's no point in making a tiny yield warhead for what NK wants them for, when you can make a larger one for the same size/weight or for less.

[The Duchess of Zeon]

Alright, so I'm off with that. It's interesting that their final agreed yield for the first device was actually about as high as I'd estimated for this one--at the time, I'd seen a lot of people dismiss it as only a few dozen tons or so, and definitely a fizzle. It seems that one of the reasons for taking the North's nuclear ability seriously is that the ultimate estimates were revised upwards, and here they reflect that. So, it's a real nuclear capability, though 4kT would tend to imply a somewhat smaller than average device, the question being if it's physically smaller, i.e., more capable of being used as a missile warhead.

I'm under the impression that smaller, simpler and cheaper warheads would still have larger yields than that. There's no point in making a tiny yield warhead for what NK wants them for, when you can make a larger one for the same size/weight or for less.

Well, part of it is that this is based on existing technological development. The US/USSR etc didn't need a very small nuclear device right from the start, they were being delivered by B-29s, not missiles. There may be some ability to reduce the size of a nuclear device, with a corresponding reduction in yield, using more brutally simple techniques as opposed to the highly refined ones which allow us to make much smaller AND more powerful warheads.