Presidential candidate Barack Obama says he would not use nuclear weapons "in any circumstance" to fight terrorism in Afghanistan and Pakistan, drawing criticism from Hillary Rodham Clinton and other Democratic rivals. "I think it would be a profound mistake for us to use nuclear weapons in any circumstance," Obama said, and added after a pause, "involving civilians." Then he quickly added, "Let me scratch that. There's been no discussion of nuclear weapons. That's not on the table." Obama was responding to a question by The Associated Press about whether he could envision any circumstance in which he would be prepared or willing to use nuclear weapons in Afghanistan or Pakistan to against terrorist hideouts or al-Qaida leader Osama bin Laden. "There's been no discussion of using nuclear weapons, and that's not a hypothetical that I'm going to discuss," Obama said after a Capitol Hill breakfast with constituents.