“During the nearly 15 years since the United States went to war in Afghanistan, the number of American troops there spiraled to 100,000, then dropped slightly below 10,000. President Barack Obama had planned to drop the number to 5,500 by the end of this year. Now he has decided to leave about 8,400 through the end of his presidency.”
Source: A timeline of U.S. troop levels in Afghanistan since 2001