IAEA chief Muhammad el-Baradei secured the agreement in talks in Tehran at the weekend. But the United States has already said the accord does not touch upon the core issue, namely the refusal of Iran to halt uranium enrichment.
It looks, however, as though it will help unravel some of the past history of Iran's nuclear program, shedding light on activities carried on for many years in conditions of secrecy.
The agreement el-Baradei carried away with him from Tehran on January 13 deals with two issues.
One relates to so-called military-linked studies. These include indications that Iran was examining how to convert uranium dioxide into a semi-refined product called UF4, which can be refined further into gas suitable for an enrichment cascade; and among other things, that Iran was studying designs for missile reentry vehicles.
The second issue relates to radioactive contamination found at an Iranian technical university. The IAEA wants to know how this uranium contamination got there, and it wants access to the individuals working at the university, as well as to the equipment that was used.
These two areas that Iran has agreed to explain within a month are the remaining unanswered questions on a "work plan" formulated by the IAEA last year, and endorsed by the agency's Board of Governors on November 15, 2007.
U.S. White House spokesman Gordon Johndroe, who is traveling with President George W. Bush in the Middle East, on January 13 called the agreement a "step." He said it's useful to know more about Iran's past nuclear activities.
But Johndroe said this does not have any bearing on today's big issue -- that Iran is continuing with uranium enrichment, a process that could feed into a nuclear weapons' program.
Bush made clear at the start of his Mideast tour that the United States intends to pursue its objective of making enrichment a price too high for Iran to pay.
"Economic pressure, financial sanctions, will cause the people inside Iran to have to make a considerate judgment about whether or not it makes sense for them to continue to enrich [uranium] or face world isolation," Bush said.
During his tour, Bush has warned Mideast leaders against Iran's intentions, and has condemned the lack of transparency in Iranian nuclear affairs.