Head of Federal Security Service of Russia (FSB) Aleksandr Bortnikov said that Doku Umarov, the Chechen leader of the Caucasian Emirate terrorist organization, was killed in a "combat operation” this year. The circumstances of his death, a major feat of Russian counterterrorism agencies, were not revealed. DEBKAfile: Umarov was al Qaeda’s highest profile commander in the Caucasus. He was not only Russia’s most wanted man, but also on the wanted terrorist lists of the US and UN Security Council. Umarov took responsibility for organizing such atrocities as the suicide bombing that killed 37 people at a Moscow airport in January 2011 and the "Nevsky Express" 2009 train explosion which killed 28 people.