President Obama has said that our aspirations should be realistic. We are not going to turn one of the poorest countries in the world, that was plunged into 30 years of war, into an advanced, industrialized, Western-style democracy. What we want to achieve is Afghanistan's capacity to secure and govern itself.

Iraq has gone from being on the brink to being on the mend, and it clearly has some big advantages.

I am neither a pessimist nor an optimist. I am a realist, and the reality in Iraq is that it has been very hard and it continues to be hard.

I did a week-long assessment in 2005 at (then Defense Secretary Donald) Rumsfeld's request. Following our return, I told him that Afghanistan was going to be the longest campaign of what we then termed "the long war."

The Islamic State fighters in Mosul are dead men walking and I think they increasingly know it.

The job of the leader is to get the big ideas right.

I just don't know whether it was all destroyed years ago - I mean, there's no question that there were chemical weapons years ago - whether they were destroyed right before the war, (or) whether they're still hidden.