His inner circle called him The Doctor, because of his Ph.D in mathematics. Some of his operatives called him Our Big Brother. The Central Intelligence Agency called him by a code name — which intelligence sources reveal as Pulsar One. Whatever you call him, Ahmad Abdul Hadi Chalabi, a shrewd Iraqi Arab from a family of Shiite bankers, literally changed the world. The United States, which he referred to so respectfully as a “strategic ally,” had sponsored him, flown him and his people to Iraq, even toppled Saddam Hussein for him, as he would boast. The Iraq War has many critics and some fierce defenders, but many insiders on both sides of the debate agree on this: without Chalabi there would have been no war.