VENICE (AP) ― Director Errol Morris spent 33 hours interviewing Donald Rumsfeld for his new documentary “The Unknown Known.” But Morris says the former U.S. defense secretary proved hard to fathom.

The director said Wednesday at the Venice Film Festival that he cannot tell if Rumsfeld, who narrates the film, was putting on a “performance” or being himself.

“The Unknown Known” is competing for the top Golden Lion award. Morris’ “The Fog of War” won an Oscar in 2003 for its look at Robert McNamara, secretary of defense during the escalation of the Vietnam War.

His latest documentary analyzes the U.S. decision to go to war in Afghanistan and Iraq. It includes clips from Pentagon news conferences as it offers an unflinching look at Rumsfeld’s career through his own words.