LOS ANGELES — Interviewing Sen. Ron Wyden, D-Ore., about drone warfare was both frustrating and enlightening, the director of the new documentary “Dirty Wars” told a sold-out screening here about talking to the member of the Senate Intelligence Committee about classified targeted-killing campaigns.

“It was completely comical sitting down there in that interview,” Richard Rowley told an after-film discussion audience on June 7 about his visit with Wyden.

During the Capitol Hill interview for the film, aides interjected to tell Wyden what he could and could not say to Rowley and Jeremy Scahill, investigative journalist for The Nation and the central figure in the film. It opened in Washington on June 7.

At one point in the film, Scahill asks Wyden a question and the senator looks off-screen and asks, “Is that classified?”

Wyden, who as a member of the Senate Intelligence Committee is privy to a bevy of government secrets, has been a vocal advocate of more transparency in the Obama administration’s drone warfare strategy.

In March, Wyden voiced support for Sen. Rand Paul’s filibuster of John O. Brennan’s nomination to be CIA director over the drone issue. Although Wyden supported Brennan’s nomination, on the floor he said he supported the Kentucky Republican’s effort to get answers on the rationale and civil liberty concerns about targeted killings.

The release of “Dirty Wars” comes on the heels of the revelation of the National Security Agency’s sweeping data collection program known as PRISM. Discussing the leak in a

known as PRISM. Discussing the leak in a Huffington Post article, Jennifer Hoelzer, Wyden’s former deputy chief of staff and communications director, wrote, “Seriously, do you have any idea how frustrating it is to have your boss ask you to get reporters to write about something he can’t tell you about?”

Watch the trailer for “Dirty Wars”:

“Wyden is a voice in the wilderness in the Senate,” Rowley said June 7.