Well, Nigeria has played a constructive role in peacekeeping in various parts of West Africa. But unless and until Nigeria itself is democratic and respects human rights, it too may well be a source of much greater instability as political repression limits the ability of the people of Nigeria to achieve their full potential.

If you're trying to get something done, there will always be people who don't want to see you get something done, or who have a stake in the status quo. And if they approach that through ad hominem criticism of you, you've got to have enough confidence and thickness of skin to be able to endure.

President Obama is an extraordinary person to work with and for.

We should learn to tolerate nuclear weapons of North Korea just like we did the Soviet Union.

I was working with a number of African heads of state. And after their initial surprise, I think many of them just treated me as they would anybody else. They had to deal with me as a representative of the United States of America, and the United States of America was too important to be dismissed or ignored on any grounds.

We know that weapons, heavy weapons continue to flow across the border from Russia into Ukraine. And we have now, in recent days, indications that Russians - Russian military units themselves have, on occasion, fired into Ukraine.

You have to make change.