A mild-mannered 64-year-old Japanese career diplomat, Yukiya Amano managed to spark a wide range of emotions in power centers around the globe: warm smiles in Washington, Paris and London; a torrent of vitriol in Tehran; ruffled feathers in Moscow and Beijing. That's because as director general of the International Atomic Energy Agency, Amano turned up the heat on Iran with a report giving his U.N. body's imprimatur to the accusation that Iran may have done research work on nuclear weapons. That report has prompted Western powers to ratchet up sanctions, although Russia, China and other skeptics have not followed suit. And as tension rises, Amano could find himself at the center of the storm in 2012.
Correction: The original article incorrectly referred to Amano as Yukio Amano and stated that he had been director general of the International Atomic Energy Agency for less than a year. He's held the position since December 2009. TIME regrets the errors.