BAGHDAD — Vice President Dick Cheney on Monday made a surprise visit to Baghdad, where he pledged that U.S. forces would ‘not quit before the job is done’ and said that a massive troop buildup had achieved ‘phenomenal’ improvements in security. At sunset Monday, however, a female suicide bomber killed at least 40 people and injured more than 50 when she blew herself up in a crowded pedestrian area near a Shiite Muslim shrine in the southern holy city of Karbala, according to government and hospital officials. Among the victims were several Iranian pilgrims who’d come to worship at the Imam Hussein shrine, one of Islam’s most sacred sites. And the U.S. military announced the deaths of two soldiers who were killed Monday when their Humvee struck a roadside bomb north of Baghdad, bringing the number of American troop deaths to at least 3,990 since the war began. Cheney told a news conference in Baghdad that the invasion of Iraq five years ago this week was a ‘difficult, challenging, but nonetheless successful endeavor.’ However, he said that obstacles remain and that the decision on whether to begin reducing forces depends on political reconciliation and the ability to […]