It might be wise for the United States to resign itself to Iran's development of nuclear weapons and to focus on deterring the Islamic Republic from ever using them. But U.S. leaders have explicitly rejected that course of action. "Make no mistake: a nuclear-armed Iran is not a challenge that can be contained," U.S. President Barack Obama told the UN General Assembly last September. "And that's why the United States will do what we must to prevent Iran from obtaining a nuclear weapon." U.S. officials have also made it clear that they consider direct military action to prevent Iran from acquiring a nuclear weapon an extremely unattractive option, one to be implemented only as a regrettable last resort.