HAVANA - SEPTEMBER 03:  Former Cuban leader Fidel Castro gestures during an appearance in front of Cuban students on the stairs of the University of Havana September 3, 2010, in Havana, Cuba. In his first open air speech since he fell ill on July 26, 2006, Castro warned of a possible nuclear war, triggered by the Iran crisis and called on the world to persuade U.S. President Barack Obama to avoid war. Castro called for the meeting with the youth just three days before the official start of the Cuban school year.  (Photo by Sven Creutzmann/Mambo Photo/Getty Images)