The United States formally withdrew its military forces from Iraq on Wednesday, Sept. 30, concluding a presence that began with the 2003 invasion ordered by President George W. Bush. The departure was marked by a low-key ceremony. In Baghdad, Iraqi security officers rode in a convoy celebrating the withdrawal, waving victory signs and displaying national flags, according to an image caption accompanying the report. The formal exit closes a major chapter in U.S. involvement in Iraq, though American military forces have been present in the country during much of the past 35 years. The withdrawal comes more than 23 years after the invasion, which began with the U.S. military campaign known as “shock and awe.” Iraq’s future remains uncertain as it enters a new period without U.S. troops, the report said. The withdrawal’s implications for the country and U.S. influence in the region were not detailed in the announcement of the departure.