Chuck Hagel on resigning: "You have to know when to leave"

Defense Secretary Chuck Hagel offered a few thoughts on his impending departureThursday, telling reporters that in addition to being aware of the challenges the country faces, "you have to know when to leave, too."

President Obama announced Hagel's resignation just before Thanksgiving, although he is expected to stay on until his successor is named. Mr. Obama will announce his new nominee, widely expected to be former Deputy Defense Secretary Ashton Carter, on Friday.

CBS News National Security Correspondent David Martin has reported that Hagel was fed up with micromanagement from the White House, while the White House was unhappy that Hagel was not a vocal defender of the administration's policies. Sen. John McCain, R-Arizona, later echoed that assessment, telling a local radio station Hagel was "very, very frustrated."

Asked about McCain's comments, Hagel said, "There were no major differences in any major area. Sure, there are always issues of style, and how you get things done, and are things moving fast enough, but this country, as I've said, is well served to have a president like President Obama, who is thoughtful, who is careful. This is a time that a powerful nation, the most powerful nation on Earth, must be very wise in its implementation of its power.

Here's what else Hagel had to say:

On handing over the reigns of the Defense Department: "And the preparation of an institution is probably the most significant responsibility a leader has to hand, that off to someone who is coming in behind you. And the discussions the president and I had were about the next two years. How is he best prepared to lead this country? And how is this institution best prepared to do the things that he must have assurance that are prepared to do, options, capabilities, capacities?...I'm proud of my leadership over here, how we've done it. But the next two years is another -- another zone, I think, of kinds of challenges for this country. And leaders have to be wise enough to know that. And as we talk through it, the president and I did, we both came to the conclusion that I think the country was best served with new leadership. He thought it was over in this institution, after we had talked through it."

On his relationship with President Obama: "There were just two of us in the room during these discussions. And we had some very direct and very honest relationships. I would also say that, as the president has said, the president is a friend. I consider him a friend. He's said that about me, which I appreciate. Friends can talk plainly to each other. He's president of the United States. I serve at the pleasure of the president of the United States. But we talked as friends. We talked as Americans. We talked as senior leaders for this country who both have awesome responsibility."

On the length of his tenure: "I didn't come into this office with any preconceived notion I'm staying four years, one year, three years. This is a business that -- that's always unpredictable. You recognize that going in. So I never said I would be here two years or four years...No one ever knows about a job, especially a big job, until you get in it, until you're the actual practitioner of the job. Now, you can read about it. Your predecessors can tell you about it. You can think you know about it, and you can write about it and broadcast about it, but nobody knows about these jobs."

On speculation he couldn't handle the challenges the department faced: "Whether I thought I could do the job, whether it was ISIL or any other challenge, that wasn't the issue. What I said here just a moment ago was, as you look forward, the next two years, and the challenges that are coming, as I thought through it, as the president and I talked about it, I think fresh leadership is not unimportant in all areas. But the president and I had a long -- actually had more than one conversation about all this -- and so it wasn't a matter of was ISIL too much or the budgets too much. No."

On his career: "Forty-six years ago today, I arrived at Oakland, California, on a transit back from Vietnam, after I'd spent one year in Vietnam, 46 years ago today. If anybody would have told Sergeant Hagel walking off that plane with my duffel bag where I'd be 46 years down the road, that would have been pretty hard for me to believe it. I mean, the privileges I've had have just been tremendous."