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Are North Korea's nuclear weapons small enough to fit a ballistic missile?

North Korea claims to have made progress on miniaturized nuclear devices. Some experts credit that claim, but much of what North Korea can or can't do remains unknown.

By Staff Writer / April 8, 2013

A visitor poses in front of North Korea's mock Scud-B missile (c.) and other South Korean missiles on display at Korea War Memorial Museum in Seoul, South Korea, on April 13. South Korea’s top security official said Sunday that North Korea may be setting the stage for a missile test or another provocative act.

Ahn Young-joon/AP



Can North Korea make a nuclear warhead small enough to fit atop a ballistic missile? That’s a key question facing the US and its allies in East Asia as tensions continue to roil the Korean Peninsula.

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Following its Feb. 12 nuclear test, Pyongyang boasted that it had detonated a “miniaturized and lighter nuclear device." Some US experts interpreted this to mean that North Korea is claiming to have developed a weapon that would fit on a Nodong medium-range rocket or, perhaps, even the untested, longer-range KN-08. This would threaten South Korea and perhaps Japan, but not the US mainland itself.

“The question is, do we believe them?” writes nuclear expert Jeffrey Lewis of the James Martin Center for Nonproliferation Studies in Foreign Policy magazine.

The public US government position is that it does not know how far down the road toward miniaturized nuclear devices North Korea has progressed. In 2005, the director of the Defense Intelligence Agency told a congressional hearing that North Korea had the capability to arm a missile with a plutonium-based nuclear device, but Pentagon officials later backed away from that conclusion, according to a 2013 Congressional Research Service report on technical issues related to North Korea’s nuclear weapons.

“It is possible that Pakistani scientist A.Q. Khan may have provided North Korea the same Chinese-origin nuclear weapon design he provided to Libya and Iran,” writes CRS expert Mary Beth Nikitin. “Even though that design was for a [highly enriched uranium] based device, it would still help North Korea develop a reliable warhead for ballistic missiles – small, light, and robust enough to tolerate the extreme conditions encountered through a ballistic trajectory.”

For his part, Mr. Lewis of the Center for Nonproliferation Studies is inclined to take seriously North Korea’s statements about its progress in miniaturization. He bases this view, in part, on circumstantial evidence: the smallish yields of the first two North Korean nuclear tests, in 2006 and 2009.

“North Korea’s disappointing yields in 2006 and 2009 [nuclear tests] are not the result of technical incompetence so much as outsized ambition,” Lewis writes. “The North Koreans tried to skip some steps and go directly to miniaturized devices.”

In other words, Pyongyang is not following the same process of weapons development used by superpowers such as the US and the Soviet Union. Instead,  North Korea may be attempting to leapfrog ahead to missile-deliverable devices based on the experience and knowledge gathered by smaller members of the nuclear club, particularly Pakistan.


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