"The United States and its partner countries are reducing military involvement in Afghanistan as Afghan security forces assume lead security responsibility throughout the country. The current international security mission terminates at the end of 2014 and has been expected to transition to a smaller mission consisting mostly 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, was reduced to a 'pre-surge' level of about 66,000 by September 2012, and to about 34,000 as of February 2014. A number of options for the size of a 'residual force' that will remain in Afghanistan after 2014 are under consideration in the United States and in NATO countries. The widely preferred option is for about 12,000 trainers and mentors, of which about two-thirds would be U.S. forces, plus a number of mostly U.S. counterterrorism forces. However, no decisions have been made on the residual force because President Hamid Karzai refuses to sign a required Bilateral Security Agreement (BSA) before he leaves office in mid-2014. All the candidates in the April 5, 2014, presidential election say they support the agreement, but a successor will likely not take office until June 2014 at the earliest, thereby constraining the U.S. and NATO force planning process. Fearing instability after 2014, some ethnic and political faction leaders are reviving their militia forces should the international drawdown lead to a major Taliban push to retake power."
CRS Report for Congress, RL30588