"On December 19, 2018, President Trump announced his intention to withdraw U.S. forces from Syria within 30 days, although Administration officials subsequently suggested that the process could take several months. Subsequent press articles indicated that the White House is also considering withdrawing 'up to half' of U.S. forces in Afghanistan in the coming months, although at the time of writing the Trump Administration has stated it has not yet ordered any such withdrawal. More recently, the United States has been negotiating with Afghan Taliban representatives regarding the conditions upon which, if met, American forces might withdraw from Afghanistan. Opinions vary as whether these negotiations might lead to a successful settlement. Regardless, the suggestion that the United States might curtail its military operational commitment to those theaters raises a number of issues which may be of interest to Congress. In particular, from a strategic perspective, when is a withdrawal from a military operation appropriate?"
CRS Insight, IN11032
Congressional Research Service: https://crsreports.congress.gov/