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MIT scientist who said N. Korean missile could hit U.S. mainland reverses view

| Sunday, April 21, 2013, 11:00 p.m.
North Korea’s Taepodong-2 missile could not hit the continental United States, Theodore Postol of the Massachusetts Institute of Technology and others say, but they note that Pyongyang’s medium-range missile, the Nodong, could hit its neighbors in eastern Asia.
North Korea’s Taepodong-2 missile could not hit the continental United States, Theodore Postol of the Massachusetts Institute of Technology and others say, but they note that Pyongyang’s medium-range missile, the Nodong, could hit its neighbors in eastern Asia.

A key scientist who predicted North Korea was developing a missile that could hit much of the United States with a nuclear-sized payload now says that possibility appears to be years off.

Massachusetts Institute of Technology professor Theodore Postol told the Tribune-Review that he revised his analysis based on more recent launches of the Taepodong-2 missile, believed to be the longest-range missile in the North's arsenal. Those launches show the missile's second stage falls well short of the power necessary to hit California and points farther east.

“This would not be all that comforting to South Koreans and Japanese,” said Postol, former scientific adviser to the U.S. chief of naval operations. He said South Korea and Japan are in range of shorter-distance missiles that could contain nuclear payloads.

Physicist David Albright and the Defense Intelligence Agency concluded that North Korea might have a nuclear device small enough to fit on the head of a missile. Postol told the Trib that such a semi-miniaturized atomic bomb would weigh about a ton. But the range of such a missile is highly variable and the likelihood “very low” that the North Koreans have perfected a nuclear payload small enough and that could withstand the intense G-forces and vibrations of an even shorter launch.

Reports this month from South Korea said that the North moved two untested Musudan missiles to the east coast and fueled at least one of them.

Some scientists believe the Musudan is an intermediate-range ballistic missile with perhaps enough boost to reach the U.S. territory of Guam. Experts say, however, that North Korea has paraded missiles that are, in fact, nothing but decoys.

For the United States, the alarm that North Korea might be able to launch a nuclear-capable missile was first sounded in the 2008 annual threat assessment by the director of national intelligence.

J. Michael McConnell then wrote that Taepodong-2 “probably has the potential capacity to deliver a nuclear-weapon-sized payload to the continental United States. But we assess the likelihood of successful delivery would be low absent successful testing.”

That warning, occurring amid bigger U.S. concerns about al-Qaida and terrorism, received little notice at the time.

But it was supported by Postol and David Wright in 2009 after an attempted launch that year of a Taepodong-2. Though unsuccessful, the attempt represented a “significant advance” in the technology and indicated a “capability to reach the continental United States with a payload of one ton or more” with certain modifications.

As North Korea issued its nuclear threats this year — warning that it was prepared to strike the United States — the Congressional Research Service sent a report to lawmakers repeating the assessment: The Taepodong-2 has the potential to hit the U.S. mainland.

The service noted that after several failures, North Korea launched a satellite in December using the Taepodong-2.

Postol said the second stage of the missile had been misjudged. Earlier thinking was that it was derived from a Soviet-era submarine-launched, intercontinental ballistic missile, called the SS-N-6, with high-energy propellant. Subsequent calculations showed that it used lower-energy kerosene and nitric acid.

The Taepodong-2 could not hit the continental United States, Postol and others said, but they stressed that North Korea does have a serviceable medium-range missile, the Nodong, that could hit its neighbors in eastern Asia. Scientists have debated its accuracy.

Albright, a physicist and president of the Institute for Science and International Security, said he believes North Korea has had enough time and experience to miniaturize a warhead to fit atop the Nodong.

It could be made of a plutonium or enriched uranium core, but for several reasons, a plutonium weapon would be easier to miniaturize, he said. North Korea shut down its small reactor used to make plutonium in 2007 during talks to denuclearize. It recently threatened to reopen the facility, called Yongbyon.

Scientists with the National Academy of Engineering estimate that before its shutdown, Yongbyon produced 24 to 42 kilograms of plutonium, enough for four to eight bombs.

In a parallel effort, North Korea has sought to build a uranium enrichment program for a uranium-core bomb. It's unclear how far along that program has developed.

Most scientists believe North Korea has used some of its nuclear material to conduct three deep underground tests: in 2006, 2009 and this year. The first test produced a small yield for a nuclear device and most scientists believe it was a fizzle. Atmospheric samples indicated it used a plutonium core.

The next two tests were larger, but scientists say they did not produce detectable radioactive atmospheric samples, so it's not known what material was used.

Even if it has developed a miniaturized warhead, Postol said he does not believe North Korea would launch one on the Nodong without testing whether it could survive.

That said, Postol noted that North Korea's leader, Kim Jong Un, is equally untested. He said South Korea's hard-line president, Park Geun-hye, has offered ways for the North to back away from confrontation and save face — an important factor in Korean culture.

“But if (Kim) is too stupid to take a face-saving offer, then (the situation) is very dangerous,” Postol said.

Lou Kilzer is a Trib Total Media staff writer and former editor of one of South Korea's largest daily newspapers. Reach him at 412-380-5628 or

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