How many US troops are there in Afghanistan?

100,000.

In November 2009, US President Barack Obama announced the addition of some 30,000 troops to the more or less 68,000 US troops deployed in Afghanistan at the that time. This brings the total number of US troops to 100,000 by the start of 2010. The same fact has been acknowledged by the United Nations Security Council in January 2010 as well as US Secretary of State Hillary Clinton at the International Conference on Afghanistan.