OSAKA — A recent report by 16 U.S. intelligence agencies that concluded Iran halted its nuclear weapons development program in 2003 is likely to present new opportunities and challenges to Japan, whose relations with Tehran have blown hot and cold over the past decade.

The National Intelligence Estimate report, released last month, judged that not only had Iran abandoned plans for a nuclear weapon in 2003 but also that U.S. intelligence was moderately confident Tehran had not restarted its nuclear weapons program as of mid-2007. It expressed moderate to high confidence that Iran does not currently have an atomic weapon.

Iran's leaders welcomed the report, saying it clearly vindicated their long-standing claim the nation's nuclear program is only for peaceful purposes. But in Washington the report created a political firestorm, with current and former members of President George W. Bush's administration, as well as the president himself, commenting that Iran was still a threat.