Al Qaeda in Iraq and its presumed leader, Abu Musab Zarqawi, have conceded strategic defeat and are on their way out of the country, a top U.S. military official contended yesterday. The group's failure to disrupt national elections and a constitutional referendum last year "was a tactical admission by Zarqawi that their strategy had failed," said Lt. Gen. John R. Vines, who commands the XVIII Airborne Corps. "They no longer view Iraq as fertile ground to establish a caliphate and as a place to conduct international terrorism," he said in an address at the Washington Institute for Near East Policy....