By Mark Hosenball and Matt Spetalnick
WASHINGTON (Reuters) - The Obama administration on Friday played down a Pentagon spy agency report that triggered alarm that North Korea might be able to deliver a nuclear-tipped missile at a time of heightened tensions in Asia and the United States over Pyongyang's threats of war.
The evaluation from the Pentagon's Defense Intelligence Agency (DIA), produced in March and revealed at a congressional hearing on Thursday, concluded that North Korea likely has nuclear bombs that could be delivered by missiles.
The DIA has been issuing similar public warnings since 2005, but U.S. defense and intelligence officials cast serious doubt on whether North Korea can, in fact, fire a nuclear missile.
The latest warning surfaced as Western and Asian governments struggle to determine how far North Korea's young and untested leader Kim Jong-un will take his bellicose threats and missile tests, another of which might be carried out in the coming days.
Figuring out North Korean capabilities has been a vexing challenge for the United States and other countries because North Korea is one of the most reclusive and opaque nations in the world.
In Seoul, U.S. Secretary of State John Kerry poured cold water on the DIA report and said it is "inaccurate to suggest that the DPRK (North Korea) has fully tested, developed capabilities" as implied in the document.
A source close to the Obama administration's policymaking on North Korea, speaking on condition of anonymity, said the DIA report was considered "very preliminary" inside the Pentagon and did not prompt any changes in U.S. military contingency planning.
But the DIA's assessment did not come out of the blue. The Pentagon's intelligence arm has been warning since as far back as 2005 that Pyongyang might be able to put an atomic bomb on a missile.
Two previous heads of the DIA made the same claim eight years ago and again in 2011, although their assessment of North Korea's nuclear capability has never been fully corroborated and there is debate in U.S. intelligence circles about it.
Gary Samore, who until earlier this year was the top nuclear proliferation expert on President Barack Obama's national security staff, said it looks like there "is not enough evidence to reach a conclusion either way" on whether North Korea is capable of building and deploying a nuclear warhead on a missile.
The DIA gathers information about the capacity and strategic intentions of foreign militaries. Like other intelligence agencies, it was criticized after the start of the Iraq war in 2003 for having been too bullish in asserting that Saddam Hussein's government had possessed weapons of mass destruction. No such weapons were found after the U.S.-led invasion.
A senior U.S. official, speaking on condition of anonymity, characterized the latest DIA paper as "relatively low level" and added that it "never got to senior levels of the U.S. government." The official added that it was classified "Secret," which is a mid-level classification, far below the secrecy levels applied to the most sensitive U.S. intelligence reports.
The DIA report was not a factor in the U.S. decision to stage a flyover of B-2 stealth aircraft over South Korea last month as part of joint exercises or the deployment of missile interceptors to Guam and Alaska, said the source close to the administration's policymaking on North Korea.
A little-known U.S. lawmaker, Representative Doug Lamborn, set off alarm bells on Thursday when he read a small section of the DIA report on North Korea at a hearing in the House of Representatives Armed Services Committee.
The passage said the DIA had "moderate confidence" that North Korea has nuclear weapons that are capable of delivery by ballistic missiles.
The previous head of the DIA, Lieutenant General Ronald Burgess, told the Senate Armed Services Committee something similar in March 2011, although he put it in stronger terms.
"The North may now have several plutonium-based nuclear warheads that it can deliver by ballistic missiles and aircraft as well as by unconventional means," he said, according to a transcript of the hearing.
Burgess' comment received little media attention but the Korean peninsula has become more unstable since then as young, new leader Kim tries to establish his credentials as a strong figure.
An earlier DIA chief, Vice Admiral Lowell Jacoby, also raised similar concerns about North Korea before the same Senate committee in April 2005. "The assessment is that they have the capability to do that, yes, ma'am," Jacoby replied to a question from then-Senator Hillary Clinton about whether North Korea has the ability to arm a missile with a nuclear device.
His agency later played down his evaluation as theoretical.
North Korea has deployed as many as five medium-range missiles on its east coast in recent days, 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 latest DIA report said any North Korean nuclear missile would probably be unreliable.
The passage on possible nuclear missiles became public because it was erroneously marked as unclassified, some U.S. officials said.
Lamborn, the Republican from Colorado who drew attention to it, has been a leading advocate in the House against cutting spending on missile defense systems. His congressional district contains several installations involved in Air Force activity and an anti-missile program.
(Editing by Alistair Bell and Will Dunham)