BARACK OBAMA’s administration has promised to withdraw all American troops from all of Iraq’s towns by the end of this month. As the deadline looms, people are again asking whether Iraq’s forces will be able to cope on their own. On cue, a fresh bout of violence has erupted. On June 20th, a huge lorry bomb exploded in Taza, a Turkmen town just south of the disputed city of Kirkuk, killing at least 70 people. Two days later at least seven bombs went off in and around Baghdad, including a roadside blast, a car bomb and a suicide attack, killing...