The debate, in essence, is a mirror image of the intelligence dispute on the eve of the Iraq war.

This time, United States spy agencies are delivering more cautious assessments about Iran’s clandestine programs than their Western European counterparts.

The differing views color how each country perceives the imminence of the Iranian threat and how to deal with it in the coming months, including this week’s negotiations in Geneva — the first direct talks between the United States and Iran in nearly 30 years.