The ultimate success of the U.S. and Israeli strikes, and so Trump's decision to intervene militarily, depends on how Iran chooses to react. Some analysts fear this action will accelerate Iranian efforts to build a nuclear weapon, with hardliners in Tehran now viewing it as an urgent priority.

Pentagon reports Iran's nuclear facilities were "completely obliterated" in June strikes, offering a more optimistic assessment than earlier estimates while Iran acknowledges damage.

Opinion: Analysts will need more intelligence from more sources to make a confident judgment about the effects on Fordo and Iran’s broader nuclear efforts.