As much as Trump will try to spin it, what this announcement represents is a continuation of the Obama administrations Afghan policy. Trumps 12,000 troop level is much more similar to Obama's draw down level of 8,400 troops than it is to the 100,000 U.S. troops in the country in 2010 when we were actually fighting a war there. There isn't any noticeable change in the mission, either. Obama had long ago abandoned Bush's"nation building" in Afghanistan, and the troops he had there at the end of his administration were focused on pretty much the same mission Trump just articulated.