FACTBOX: U.S. says Iran halted nuclear arms program

(Reuters) - U.S. intelligence agencies concluded in findings released on Monday that Iran stopped its nuclear weapons development program in 2003. Following are highlights of the National Intelligence Estimate's key judgments.

-- Iran had a nuclear weapons program but halted it in 2003 and had not restarted it as of mid-2007. The halt applied to design and engineering of an explosive device, such as fuses or shielding, and to covert uranium-conversion activities, according to senior intelligence officials. Other activities such as civilian uranium enrichment and missile development continue.

-- Iran is keeping open the option of developing nuclear weapons, but U.S. intelligence agencies "do not know" whether it currently intends to develop nuclear weapons. This is a major change from a 2005 intelligence estimate which concluded that Iran was "determined to develop nuclear weapons."

-- The weapons program was halted in response to international pressure, meaning Tehran may be more susceptible to influence than previously thought.

-- Tehran's decisions on nuclear weapons are guided by a consideration of the costs and benefits of its actions, rather than "a rush to a weapon" regardless of political and other consequences.

-- Iran would be technically capable of producing enough highly enriched uranium for a nuclear weapon by late 2009, but this is unlikely and a time frame of 2010-2015 is more likely.

-- Iran still faces significant problems operating the centrifuges needed to make enriched uranium, despite progress this year installing them at its Natanz facility.

-- It will be hard to persuade the Iranian leadership to renounce nuclear weapons development altogether.

-- Iran may have imported at least some weapons-grade nuclear fuel but not enough to make a weapon. It cannot be ruled out that Iran has acquired from abroad, or will acquire, a nuclear weapon or sufficient nuclear fuel to make one.

-- Any production of highly enriched uranium for nuclear weapons would probably take place at a covert facility rather than a declared nuclear site. Covert enrichment programs were probably halted in 2003 and had not been restarted as of mid-2007.

-- Iran has the scientific, technical and industrial capacity eventually to produce nuclear weapons if it decides to do so. Senior intelligence officials said the major hurdle is acquiring sufficient nuclear fuel.

(Reporting by Randall Mikkelsen; Editing by Patricia Wilson and John O'Callaghan)