By Dan Lamothe and Liz Sly, The Washington Post President Donald Trump has ordered a withdrawal of virtually all U.S. forces from northern Syria in the face of a Turkish military offensive targeting Kurdish fighters in the region, Defense Secretary Mark Esper said Sunday, after days of assurances from the Pentagon that the United States was not “abandoning” its partners in the campaign against the Islamic State. The order to remove the troops came toward the end of a chaotic day in which the viability of the U.S.