U.S. intelligence agencies are quietly revising their widely disputed assertion that Iran has no active program to design or build a nuclear bomb. Three U.S. and two foreign counterproliferation officials tell NEWSWEEK that, as soon as next month, the intel agencies are expected to complete an “update” to their controversial 2007 National Intelligence Estimate, which concluded that Tehran “halted its nuclear weapons program” in 2003 and “had not restarted” it as of mid-2007.

Yet two of the U.S. sources caution the new assessment will likely be “Talmudic” in its parsing. They say U.S. analysts now believe that Iran may well have resumed “research” on nuclear weapons–theoretical work on how to design and construct a bomb–but that Tehran is not engaged in “development”–actually trying to build a weapon. “The intelligence communityis always reluctant to make a total retreat because it makes them look bad,” says the third American.

This distinction between research and development is unlikely to satisfy hardline critics, who say the intel agencies, burned for overestimating Saddam Hussein’s weapons-of-mass-destruction program, have underplayed Iran’s bomb-building efforts. But the U.S. officials insist it’s an accumulation of fresh intelligence, not political or diplomatic pressure, that prompted the reconsideration.