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.

My task over the last two years hasn't just been to stop the bleeding. My task has also been to try to figure out how do we address some of the structural problems in the economy that have prevented more Googles from being created.

These kinds of tragedies [like shooting in Fort Lauderdale] have happened too often during the eight years that I've been president. The pain, the grief, the shock that they must be going through is enormous. I've asked me staff to reach out to the mayor down there and make sure that coordination between the state and local officials is what it should be. But I think we'll find out over the next 24 hours exactly how this happened and what motivated this individual.

Stamina. There is a greater physical element to this job than you would think, just being able to grind it out. And I think your ability to not just mentally and emotionally, but physically be able to say, "We got this. We're going to be OK."

Environmentalism is not an upper-income issue, it's not a white issue, it's not a black issue, it's not a South or a North or an East or a West issue. It's an issue that all of us have a stake in. And if I can do anything to make sure that not just my daughter but every child in America has green pastures to run in and clean air to breathe and clean water to swim in, then that is something I'm going to work my hardest to make happen.

My hope is that's something [Donald Trump] is thinking about, because not only is the president of the United States somebody that the entire country looks to for direction but sets the agenda internationally in a lot of ways.

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.