From the summary: "As of January 1, 2015, the United States and its partner countries have completed a transition to a smaller post-2014 mission consisting mostly, but not exclusively, of training the Afghanistan National Security Forces (ANSF). The number of U.S. forces in Afghanistan, which peaked at about 100,000 in June 2011, has been reduced to about 10,000, of which most are trainers and advisers as part of a 13,000-person NATO-led 'Resolute Support Mission.' About 1,000 of the U.S. contingent are counter-terrorism forces that continue to conduct combat, operating under a new U.S. 'Operation Freedom's Sentinel' that replaced the post-September 11 'Operation Enduring Freedom.' President Obama directed in May 2014 that the U.S. force will shrink during 2015 to about 5,000 by the end of this year, and their presence after 2015 will be exclusively in Kabul and at Bagram Airfield. The post-2016 U.S. force is to be several hundred military personnel, under U.S. Embassy authority. However, in late March 2015, in conjunction with a visit to Washington, DC, by Afghan President Ashraf Ghani and Chief Executive Officer Dr. Abdullah Abdullah, President Obama announced that U.S. forces would remain at about 10,000 through the end of 2015. He said there has not, at this point, been a change in the size in the post- 2016 U.S. forces."
CRS Report for Congress, RL30588