A look at the war in Afghanistan by the numbers:
— Start of the war: Oct. 7, 2001.
— Number of U.S. troops in Afghanistan: 88,000.
— Number of U.S. troops in Afghanistan at the war's peak: About 101,000 in 2010. Allies provided about 40,000.
— Withdrawal plans: 23,000 U.S. troops expected to come home by the end of the summer, leaving about 68,000 in Afghanistan. Most U.S. troops expected to be out of Afghanistan by the end of 2014, though the U.S. is expected to maintain a sizeable force of military trainers and a civilian diplomatic corps.
— Number of U.S. casualties: At least 1,828 members of the U.S. military killed as of Tuesday, according to an Associated Press count. According to the Defense Department, 15,786 U.S. service members have been wounded in hostile action.
— Afghan civilian casualties: According to the United Nations, 11,864 civilians were killed in the conflict between 2007, when the U.N. began reporting statistics, and the end of 2011.
— Cost of the war: $443 billion from fiscal year 2001 through fiscal year 2011, according to the Congressional Research Service.
— Number of times Obama has visited Afghanistan: 3 as president, including Tuesday, and 1 as a presidential candidate.