Across three decades and six presidential administrations, Democratic and Republican alike, one national security principle has never changed: The United States will not allow Iran to acquire a nuclear weapon. 

This consensus spans from the end of the Cold War through the post-9/11 era, and into today’s renewed conflict between Israel and Iran. Despite deep differences on foreign policy, every U.S. president since Bill Clinton has identified a nuclear-armed Iran as a line that cannot be crossed. 

Here is what they have said: 

The language may differ. The strategies have evolved. But the bottom line has not.