By Mark Hosenball and David Alexander
WASHINGTON, April 12 (Reuters) - An excerpt from a Pentagon report that set off worries about a North Korean nuclear missile appears to be a tentative assessment of Pyongyang's atomic weapons capabilities that was not intended to be released to the public.
The evaluation from the Pentagon's Defense Intelligence Agency, or DIA, concluded that North Korea likely has a nuclear bomb that can be launched on a missile, although U.S. defense and intelligence officials later cast serious doubt on whether the hermitical nation can in fact fire a nuclear missile.
It was the first time a claim from a U.S. intelligence body that Pyongyang is near to having nuclear missiles has been made public, adding to the tensions on the Korean peninsula where North Korean leader Kim Jong-un has frequently threatened war in recent weeks.
A little-known U.S. lawmaker, Representative Doug Lamborn, set off alarm bells when he read a small section of a DIA report on North Korea at a hearing in the House of Representatives Armed Services Committee on Thursday.
The passage said the DIA had "moderate confidence" that North Korea has nuclear weapons that are capable of delivery by ballistic missiles. But the report, entitled "Dynamic Threat Assessment 8099: North Korea Nuclear Weapons Program (March 2013)," seems not to be a high-level document.
General Martin Dempsey, chairman of the U.S. Joint Chiefs of Staff, told the same congressional hearing he had not read the assessment. "Well, I haven't seen it," Dempsey said. "And you said it's not publicly released, so I choose not to comment on it," he told Lamborn.
The passage on possible nuclear missiles became public because it was erroneously marked as unclassified, a U.S. official said.
Lamborn, a Republican from Colorado, acknowledged on CNN that he had only read a small portion of the report. "I have not read the entire seven-page report, I'm in the process of getting my hands on that," he said.
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James Clapper, the country's senior intelligence official, warned that the assessment was not necessarily shared by the wider U.S. intelligence community.
"I would add that the statement read by the Member is not an Intelligence Community assessment. Moreover, North Korea has not yet demonstrated the full range of capabilities necessary for a nuclear armed missile," Clapper, the director of national intelligence, said in a statement.
The DIA gathers information about the capacity and strategic intentions of foreign militaries. It was criticized after the start of the Iraq war in 2003 for being too bullish in predicting that Baghdad might have weapons of mass destruction.
North Korea will dominate talks when U.S. Secretary of State John Kerry arrives in Seoul on Friday on a trip that includes Japan and China, Pyongyang's most important diplomatic ally.
Pyongyang has deployed as many as five medium-range missiles on its east coast, according to assessments by Washington and Seoul, possibly in readiness for a test launch that would demonstrate its ability to hit U.S. bases on Guam.
Those missiles are not believed to be nuclear-armed.
The DIA report said any North Korean nuclear missile would probably be unreliable.
Greg Thielmann, a former State Department intelligence analyst now with the Arms Control Association, said that while he did not have access to the classified material apparently cited in Congress, what was said publicly about DIA's assessment sounded quite tentative.
"It really says to me that this is a speculative statement," Thielmann said. "Moderate (confidence) is higher than low confidence but it doesn't say they know very much."
It was not clear if the report was part of the U.S. military's thinking as it announced new anti-missile defenses in Alaska and Guam in recent weeks in the face of threats of war from North Korea.
"It didn't come across like the director of the intelligence community saying 'Here's what we think.' This was more sort of a document that one of the congressmen pulled out of the bag," said Hans Kristensen, a nuclear weapons analyst at the Federation of American Scientists. (Editing by Alistair Bell and Todd Eastham)