President Trump’s decision — made in the span of a week — to withdraw about 1,000 American troops from northern Syria caught the Pentagon, and the forces on the ground, off guard. To carry out the “endless wars” since Sept. 11, 2001, which Mr. Trump has vowed to wrap up, the American military has perfected the ability to build complex logistics pipelines that can funnel everything from armored vehicles to satellite internet access to gym equipment directly to combat outposts throughout the Middle East. Now, American troops are making a hasty withdrawal from Syria — under pressure from encroaching Turkish proxy forces, Russian aircraft and columns armored by the Syrian government. This means the Pentagon will have to disassemble combat bases and other infrastructure that were built to stay for a mission that was supposed to last, all while protecting the troops as they withdraw amid a chaotic battlefield. Where did U.S. troops operate before the Turkish offensive? Before the Turkish offensive, American troops, mostly Special Operations forces, operated in an archipelago of about a dozen bases and outposts across northeastern Syria, mostly living alongside their Syrian Kurdish partners. They were divided into two main headquarters, known by their cardinal…