Seven-and-a-half years ago, the United States invaded Iraq. Now, the last combat brigade has departed, as headlines from The Wall Street Journal  to Al Jazeera  proclaim. Still, U.S. troops will maintain a heavy presence in the fledgling democracy. Some 3,800 soldiers from Fort Carson's 3rd Brigade Combat Team, 4th Infantry Division, are among the roughly 50,000 military personnel who will stay to aid Iraq in an "advise and assist" role, reports the Colorado Springs Gazette . Their job is to prepare Iraqi security forces to stand on their own. The war, which lasted longer than World War II, claimed the lives of 256 soldiers on the Carson post. While the tone of the war has changed, some officials doubt that President Barack Obama will be able to meet his pledge to withdraw all troops by the end of 2011, points out Reuters , with experts warning that Iraq remains fragile.