Iran halted weapons programme 'years ago', say US chiefs

US intelligence chiefs dramatically changed their assessment of Iran's nuclear programme today.

The National Intelligence Estimate said it halted its nuclear weapons development in 2003 under international pressure.

Only two years ago, US intelligence agencies believed Tehran was determined to develop a nuclear capability and was continuing its weapons development program.

But the report warned Iran is continuing to enrich uranium, which means it may still be able to develop a weapon between 2010 and 2015.

"Tehran's decision to halt its nuclear weapons program suggests it is less determined to develop nuclear weapons than we have been judging since 2005," states the unclassified summary of the secret report, released today.

Officials said the new findings suggest that diplomacy has been effective in containing Iran's nuclear ambitions.

"This is good news in that the U.S. policy coupled with the policies and actions of those who have been our partners appear to have had some success. Iran seems to have been pressured," one of the officials said. "Given that good news, we don't want to relax. We want to keep those pressures up."

The finding comes at a time of escalating tensions between the United States and Iran, which President Bush has labelled part of an "axis of evil," along with Iraq and North Korea.

The halt to active weapons development is one of the key judgements of the latest NIE on Iran's nuclear program.

Despite the suspension of its weapons program, Tehran may ultimately be difficult to stop from developing a nuclear bomb because Iran believes such a weapon would give it leverage to achieve its national security and foreign policy goals, the assessment concluded.

To develop a nuclear weapon, Iran needs a warhead design, enough fissile material, and a delivery system such as a missile. The intelligence agencies now believe Iran halted design work four years ago and as of mid-2007 had not restarted it.

But Iran is continuing to enrich uranium for its civilian nuclear reactors. That leaves open the possibility the fissile material could be diverted to covert nuclear sites to make enough highly enriched uranium to make a bomb.

The amount of fissile material Iran has is closely linked to when it can produce a weapon. Even if the country went all out with present enrichment capability, it is unlikely to have enough until 2010 at the earliest, the officials said.

Iran would not be capable of technically producing and reprocessing enough plutonium for a weapon before about 2015, the report states. But ultimately it has the technical and industrial capacity to build a bomb, "if it decides to do so", the intelligence agencies found.