Despite international pressure, Iranian President Mahmoud Ahmadinejad listens to a technician during a visit to the Natanz Uranium Enrichment Facility, 200 miles south of the capital, Tehran, in 2008. Iranian President's Office/AP hide caption

itoggle caption Iranian President's Office/AP

Iran's Supreme Leader Ayatollah Ali Khamenei in 2009. Behrouz Mehri /AFP/Getty Images hide caption

itoggle caption Behrouz Mehri /AFP/Getty Images

Sen. John McCain, right, as he endorsed Mitt Romney's bid for the presidency earlier this month. Chip Somodevilla/Getty Images hide caption

itoggle caption Chip Somodevilla/Getty Images

People gather around a car as it is removed by a mobile crane in Tehran, Iran. The car was being driven by Iranian nuclear scientist Mostafa Ahmadi Roshan when it was targeted by a bomb Wednesday. Roshan was killed in the blast. Meghdad Madadi/AP hide caption

itoggle caption Meghdad Madadi/AP