The biggest threat that we face right now is not a nuclear missile coming over the skies. It's in a suitcase. This is why the issue of nuclear proliferation is so important. It is the - the biggest threat to the United States is a terrorist getting their hands on nuclear weapons.

American leadership is not simply a matter of going it alone and bearing all of the burden ourselves.

If we are truly created equal then surely the love we commit to one another must be equal as well

Cuba is actually one where I am more optimistic because of the unique nature of Cuba - 90 miles off our shore with a massive ex-patriot population, now Cuban-American population that still have deep links to the island. There I am more confident that over time that the winds of commerce and telecommunication and travel start shifting the nature of that regime. But that's a small country which has almost a unique relationship to us.

There are institutional obligations I have to carry out that are important for a president of the United States to carry out, but may not always align with what I think would move the ball down the field on the issues that I care most deeply about.

The people of the United Kingdom have spoken, and we respect their decision. The special relationship between the United States and the United Kingdom is enduring, and the United Kingdom's membership in Nato remains a vital cornerstone of US foreign, security and economic policy.

Let's say I'm on the policy wonk end of the spectrum. As much as I can dive into a briefing book and really work to master various subjects that come before my desk, I'm still not an expert on a huge amount of the stuff that we work on.