The U.S. began withdrawing its troops in the winter of 2007 -- 2008 .
The United States responded with a troop surge in 2007 ; the heavy American security presence and deals made between the occupying forces and Sunni militias reduced the level of violence .
The United States began withdrawing American 's troops in the winter of 2007 -- 2008 .
The United States responded with a troop surge in 2007 ; the heavy American security presence and deals made between the occupying forces and Sunni militias reduced the level of violence .