Reason to worry

Atomic Agency Concludes Iran Is Stepping Up Nuclear Work - New York Times

From the article:

Inspectors are concerned that Iran has declined to answer a series of questions, posed more than a year ago, about information the agency received from a Pakistani nuclear engineer, Abdul Qadeer Khan. Of particular interest is a document that shows how to design the collision of two nuclear spheres — something suitable only for producing a weapon....

“They are at the stage where they are doing one cascade a week,” said one diplomat familiar with the analysis of Iran’s activities, who declined to be identified because of the sensitivity of the information. A “cascade” has 164 centrifuges, and experts say that at this pace, Iran could have 3,000 centrifuges operating by June — enough to make one bomb’s worth of material every year. Tehran may, the diplomat said, be able to build an additional 5,000 centrifuges by the end of the year, for a total of 8,000.