AL-ASAD AIRBASE, Iraq (AP) — In an unannounced trip to Iraq on Wednesday, President Donald Trump staunchly defended his decision to withdraw U.S. forces from neighboring Syria despite a drumbeat of criticism from military officials and allies who don't think the job fighting Islamic State militants there is over.

Trump, making his first presidential visit to troops in a troubled region, said it's because the U.S. military had all but eliminated IS-controlled territory in both Iraq and Syria that he decided to withdraw 2,000 forces from Syria. He said the decision to leave Syria showed America'...