Afghanistan: Post-Taliban Governance, Security, and U.S. Policy [December 22, 2015] [open pdf - 2MB]
"The United States, partner countries, and the Afghan government are coping with a resilient Taliban-led insurgency after the December 2014 transition to a smaller international mission consisting primarily of training and advising the Afghanistan National Defense and Security Forces (ANDSF). The number of U.S. forces in Afghanistan, which peaked at about 100,000 in June 2011, stands at about 9,800, of which most are assigned to the 13,000-person NATO-led 'Resolute Support Mission' to train, assist, and advise the ANDSF. About 1,000 of the U.S. contingent conduct combat against Al Qaeda and associated terrorist groups under U.S. 'Operation Freedom's Sentinel' that replaced the post-September 11 'Operation Enduring Freedom.' Amid assessments that the ANDSF is having difficulty preventing gains by the Taliban and other militant groups--exemplified by the insurgent overrunning of the northern city of city of Konduz in late September 2015 and major insurgent gains in Helmand Province--President Obama announced on October 15, 2015, that about 10,000 U.S. military personnel would remain in Afghanistan through almost all of 2016, and subsequently fall to 5,500. The post-2016 force, which will remain at 5,500 for an undetermined time, is significantly larger than the U.S. force of about 1,000 personnel that was previously announced."
CRS Report for Congress, RL30588
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html