“The reason for concentrating on them,” bin Laden wrote in the 48-page document, “is that Obama is the head of infidelity and killing him automatically will make (Vice President Joe) Biden take over the presidency. … Biden is totally unprepared for that post, which will lead the U.S. into a crisis. As for Petraeus, he is the man of the hour … and killing him would alter the war's path” in Afghanistan.