Both the United States and Russia are paying close attention, trying to estimate how close Iran is to building a nuclear bomb, reports CBS News Correspondent Elizabeth Palmer.
Over America's protests, Russia has been helping Iran with its nuclear program.
Iran's popularly elected President Mohammad Khatami oversaw a project to buy a billion dollars worth of Russian technology and expertise to build a nuclear power plant in the Iranian city of Bushehr.
Until recently, the Russians swore it would only be used to generate electricity, but they claim they got a nasty shock when the International Atomic Energy Agency discovered Iran was quietly building a huge uranium enrichment plant too - which would be key to manufacturing weapons. On Monday, the agency will announce the Iranians secretly imported uranium from China for experiments.
Officially, the Russian government - which does not want Teheran to get the bomb - has reacted by demanding that all the spent fuel from the Bushehr reactor be returned. Defending this position, Russian Foreign Ministry spokesman Alexander Yakovenko says, "The spent fuel, we are bringing back. How can they use this?"
Russia also says it is pressing Iran to allow more international inspections. But it's Russia's unofficial cooperation with Iran that's most ominous. Russia is full of poorly guarded nuclear materials, and underpaid nuclear scientists who don't see why they shouldn't deal with Iran.
Vladimir Orlov of the Pir Research Institute says, "We desperately need cash. What shall we do? There is a client - Why shouldn't we provide him with that technology, those materials he seeks - when we have it."
President Vladimir Putin, meeting with President Bush two weeks ago in St Petersburg, told reporters: "The positions of Russia and the US on the issue (of nuclear cooperation with Iran) are much closer than they seem."
That's likely to be even more true with the publication of the Atomic Energy Agency's report on Monday -- but it's not the position of Russian officials the United States has to worry about - it's the clandestine activities of Russian nuclear rogues.