NEW YORK (AP) — President Barack Obama says the man behind an anti-Islam movie that ignited violence across the Middle East is a "shadowy character."

U.S. officials blame the film in part for the violence in Libya, where U.S. Ambassador Christopher Stevens and three other Americans were killed. The White House says the matter still is under investigation and that assessment could change.

Obama says Stevens was beloved by a vast majority of Libyans.

Despite the violence, he says the situation in Libya is not hopeless. But he says it will be bumpy and at times dangerous.

Obama made the comments in a taped interview with David Letterman being aired Tuesday night.