US 'exaggerating nuclear threat from North Korea'

International nuclear experts have accused the White House of exaggerating North Korea's nuclear threat to support its claim that the communist state was part of an "axis of evil" – just as it did with Iraq's before the 2003 invasion.

The accusations follow Pyongyang's first revelations about its nuclear programme under an international deal, and at the end of a week that saw an unprecedented opening up by the hermit state to the largest US cultural delegation since the Korean war.

North Korea's acknowledgement that it has 30kg of plutonium – enough for six bombs – is at the low end of Western assessments, according to experts. Although Pyongyang missed a second deadline of 25 February to come clean on all its nuclear programmes – and there are doubts that it ever will – questions are now being raised about the exact threat posed by North Korea, whose one and only nuclear test is generally thought to have been a flop.

The main focus is on North Korea's uranium programme, which could provide a second path to a nuclear weapon, but which its leaders deny having. The US accused North Korea of cheating in 2002 after intercepting a shipment of aluminium tubes which could have been used in gas centrifuges to enrich the fuel. Since then, however, America has backtracked.

"It's up there with the Iraq nuclear assessment," said David Albright, president of the Institute for Science and International Security. "It was aluminium tubes in both cases. They may have done the same (with North Korea) and weighted it far too highly." Unlike the Iraqi case, the 2002 incident did not lead to war. "But it caused a lot of damage," he said, noting that the US accusations led to the breakdown of the "grand bargain" negotiated by the Clinton administration and prompted North Korea to withdraw from the Nuclear Non-Proliferation Treaty and end a freeze on plutonium production.

Another western expert said that "it's highly unlikely that they've got a full scale programme". Now that the US had raised the enriched uranium programme as an issue, "it becomes difficult for [the North Koreans] to prove they didn't do it" – another echo of Iraq.

A second disputed area exploited by hardliners in the White House is North Korean proliferation to Syria. Israel bombed a Syrian site in September amid reports that it was a nuclear facility. "We know the North Koreans worked with the Syrians on missiles, but it's not remotely plausible on nuclear," said the expert.

The mood music around North Korea changed with last week's performance by the New York Philharmonic orchestra in Pyongyang. But the trip had been planned amid the euphoria of last October's deal in which North Korea agreed to disable its nuclear facilities in return for oil, aid and the normalising of relations with America and its neighbours.

But now, the process has stalled, with a slowdown in the delivery of heavy fuel oil and with North Korea refusing to provide further details on its nuclear programmes and proliferation.

Hans Blix, the former chief UN weapons inspector for Iraq, noted a big difference between America's two enemies: "In North Korea, there was plutonium. The Iraqis had nothing." But he, too, said that the hardliners in the Bush administration "have all the time wanted to hype things, because they ride on scare."

Bomb facts

*Nuclear test in October 2006 considered a failure – yield was a fraction of the Hiroshima explosion

*Pyongyang admitted it has 30kg of plutonium

*North Korea denies enriching uranium. Experts doubt US claims of programme to enrich uranium to weapons grade level

*No confirmation of transfer of nuclear material to Syria