N Korea Threat Graver Than Ever

Pyongyang sent the world a message last week: It is as determined as ever to develop a nuclear weapon that will fit atop a missile.

North Korea's nuclear test on Feb. 12 created a shockwave equivalent to a magnitude-5.2 earthquake. The blast also shook the foundations of the global nuclear nonproliferation movement by showing that sanctions have not persuaded the state to abandon its ambitions.

The test was the country's third and the first under young leader Kim Jong-un. The unseasoned dictator appears to see a nuclear arsenal as a tool for extracting concessions from the U.S., or at least for ensuring a long reign for himself. International pariah status, he seems to think, is a price worth paying.

For Japan, the threat has reached a new level, raising a need for new countermeasures. The government has said it will augment existing sanctions against the North, but a thorough review of Japan's own security policy is also in order.

'Smaller, lighter'

"The test was conducted in a safe and perfect way" with a "smaller and lighter A-bomb," the Korean Central News Agency, Pyongyang's official mouthpiece, reported the afternoon of Feb. 12.

The experiment, the broadcaster said, demonstrated that North Korea now possesses a "diversified" nuclear deterrent.

The U.S. Office of the Director of National Intelligence said that North Korea probably conducted an underground nuclear explosion in the vicinity of Punggye-ri, and that the blast measured several kilotons.

South Korea's National Defense Ministry estimated an explosive yield of 6-7 kilotons. For comparison, the atomic bomb dropped on Hiroshima in 1945 registered at approximately 16 kilotons.

Experts see troubling signs of progress in the North's development effort.

Both of the state's previous tests -- in 2006 and 2009 -- involved plutonium-based devices. But some South Korean analysts suspect the latest experiment involved a uranium-based boosted fission weapon, which uses nuclear fusion to generate greater explosive power.

This is worrying for a number of reasons. Given that North Korea is endowed with plentiful natural uranium deposits, a successful test of a uranium device could mean that mass production of nukes is not far off.

Boosted fission capability would mean North Korea is getting closer to developing a more powerful hydrogen bomb. And boosted fission devices are seen as relatively easy to scale down to deliverable size.

North Korea is believed to possess 100-300 medium-range Nodong missiles that are capable of striking Japan. The conventional wisdom has been that the country lacked the ability to build warheads light enough for the rockets. But if Pyongyang's claims are true, it may be on the verge of threatening Japanese cities with nuke-tipped Nodongs.

Moreover, the type of rocket North Korea launched in December has an estimated range of 10,000km, according to Japanese, American and South Korean defense officials. That would be enough to hit the U.S. mainland.

For the time being, the fear is that Pyongyang may ratchet up the tension on the Korean Peninsula even further with additional nuclear tests or rocket launches.

North Korea's Foreign Ministry described last week's nuclear test as a "primary countermeasure" and warned that Pyongyang would have "no option but to take the second and third stronger steps" if the U.S. maintains a "hostile approach."

(The Nikkei Asian Review Feb. 20 edition)

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