Via Paul Waldman, Eric Black notes that the shift in Bush’s rhetoric from warning about Iranian nuclear weapons to warning about Iranian nuclear knowledge happened back in August, suggesting that this is around the time at which the White House became aware of the Intelligence Community’s view that Iran had no active nuclear weapons program.
That’s plausible, though one can also imagine a more multifaceted process. Under this theory, Bush would have been informed of IC views some time before August, at which point they just got ignored. Then there may have been some moment when Mike McConnell or someone else important within the intelligence world got upset and said “you can’t have people saying blah blah blah” and thus begins the era of what Black calls “Clintonian parsing,” language designed to obscure the new facts while technically staying within the bounds of what the new information says. But eventually even this got to be too much and pressure was obviously brought to bear from inside the executive branch to release the NIE to the public, thus depriving the parsing strategy of much of its utility.