Iran's arms exports to the murderous Assad regime in Syria are of particular concern. As the Panel of Experts has concluded, Syria is now the central party to illicit Iranian arms transfers.

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.

It's not the day in which I grew up, long time ago, where we had three news networks. No cable, no social media, no internet. Where what you see is what you got. We had basically straight journalism. We don't have that anymore.

I have to separate my personal concerns from my professional responsibilities.

For the United States to recommit itself to the obligation that we undertook in the Nuclear Non-Proliferation Treaty that many other states undertook, which was to work towards disarmament and the eventual elimination of nuclear weapons, is something that manifestly serves our national security interests.

The larger picture here is that a North Korea with nuclear weapons adds to the larger proliferation risk.

There are plenty of meetings, receptions, dinners, and so if you are [at the U.N.] any length of time, and I was there for four and a half years, you formed pretty significant relationships with people from all over the world. And that's important to the work you do. If you're trying to rally the General Assembly to vote for something that matters to the United States, those personal relationships count.