A B-2 Spirit, the stealth jet that carries state-of-the-art bunker busters. REUTERS US intelligence has long agreed that taking out Fordow is key to disabling the Iranian nuclear program.

Iran's most fortified nuclear facility, called Fordo, is buried deep inside a mountain. Only the U.S. has the 30,000-pound bombs — often referred to as "bunker busters" — capable of reaching it.