While Iran's enrichment work has slowed slightly in recent months, "there remain a number of outstanding issues which give rise to concerns, and which need to be clarified to exclude the existence of possible military dimensions to Iran's nuclear program," according to the International Atomic Energy Agency report.
Among those concerns was a visit to Iran by "a foreign national with explosives expertise." The Vienna-based IAEA said it has been unable to engage Iran over the major sticking points highlighted in the report for more than a year, and called on Tehran to be more forthcoming.
The report comes ahead of six-nation talks on Wednesday looking into the possibility of tougher U.N. sanctions against Iran. At the meeting, the United States, Britain, France and Germany are expected to urge Russia and China to adopt a fourth round of sanctions, possibly targeting Tehran's oil interests, Reuters reported.
Iran insists it is enriching uranium in order to produce energy.
In this audio interview, NewsHour foreign affairs reporter Robert Zeliger speaks with Cliff Kupchan, Europe and Eurasia Program director at the Eurasia Group, about the meaning of the report:
---- By Robert Zeliger, NewsHour with Jim Lehrer