Herman Nackaerts of the International Atomic Energy Agency speaks to reporters at the airport in Vienna, Austria, on Sunday, Feb. 19, 2012, as he prepares to depart for Tehran for a nuclear-inspection visit. (AP Photo/AP Television News)

Herman Nackaerts of the International Atomic Energy Agency speaks to reporters at the airport in Vienna, Austria, on Sunday, Feb. 19, 2012, as he prepares to depart for Tehran for a nuclear-inspection visit. (AP Photo/AP Television News)