Former White House Press Secretary Robert Gibbs revealed in an interview on Up w/ Chris Hayes Sunday that, when he became the Obama administration’s top spokesman, he was told not to discuss the government’s secret drone program or even acknowledge its existence.

“When I went through the process of becoming press secretary, one of the first things they told me was, ‘You’re not even to acknowledge the drone program. You’re not even to discuss that it exists,” said Gibbs, now an msnbc contributor. That policy of secrecy, Gibbs said, made it difficult to deal with reporters asking about the program. Describing one such notable exchange in 2009 with Major Garrett, then of Fox News, Gibbs said, “I would get a question like that and literally I couldn’t tell you what Major asked, because once I figured out it was about the drone program, I realize I’m not supposed to talk about it.”

Gibbs added: “Here’s what’s inherently crazy about that proposition: you’re being asked a question based on reporting of a program that exists. So you’re the official government spokesperson acting as if the entire program…pay no attention to the man behind the curtain.”

The Obama administration has vastly stepped up the use of drones and targeted killings of suspected terrorists in countries like Pakistan and Yemen over the past four years, even targeting American citizens, a policy that has come under intense criticism from civil liberties advocates. For most of the president’s first term the administration steadfastly refused to acknowledge the program’s existence.

“I think you’ve seen recently the president discuss the need and desire to be more forthcoming,” Gibbs said. “I have not talked to him about this, so I want to be careful, this is my opinion, but I think what the president has seen is, our denial of the existence of the program when it’s obviously happening undermines people’s confidence overall in the decisions that their government makes.”

The Obama administration has continued to withhold information about the program, including the secret memo prepared by the Justice Department’s Office of Legal Counsel to justify the program’s legality. But in April 2012, Obama counter-terrorism adviser John Brennan formally acknowledged the program’s existence for the first time, in a speech at the Woodrow Wilson Center in Washington.

That decision, Gibbs said, may have helped boost public confidence in the drone program.

“In order to bolster that confidence and bolster the belief that we’re making those correct decisions on this policy, you do have to lift the veil some,” Gibbs said, “to both acknowledge that it exists, as he’s done, but also to do it in a way that provides better understanding.”

Additional reporting by Todd Cole.