WASHINGTON (AP) — The American combat role in Iraq appeared to expand on Thursday as U.S. Marines operating from a small outpost provided targeting assistance and artillery fire to support Iraqi troops inching forward to retake Mosul from Islamic State militants.A senior U.S. official said the Marines fired illumination rounds to help the Iraqi forces locate IS fighters, and also fired artillery rounds in support of the operation, as Iraqi troops took control of several villages on the outskirts of Makhmour, southeast of Mosul.