U.S. Marines troops to leave Sangin of Sangin 's Afghanistan . U.S. Marines will take over in Afghanistan , British defense secretary says . British forces will move to central part of Helmand . NEW : The switch of command in Sangin is in no way a defeat for British troops , but simply works well militarily , said Michael Clarke , director of the Royal United Services Institute , an independent defense and security think tank in London . Analyst says move is not a defeat and that it makes sense .
U.S. Marines troops to leave Sangin of Sangin 's Afghanistan . U.S. Marines will take over in Afghanistan , British defense secretary says . British forces will move to central part of Helmand . NEW : Analyst says move is not a defeat and that it makes sense .