I think that there's a power in that [information through tweets and sound bites ]. There's also a danger, what generates a headline or stirs up a controversy and gets attention isn't the same as the process required to actually solve the problem.

For the first time, preventing nuclear proliferation and nuclear terrorism is now at the top of America's nuclear agenda.

I'm not somebody who is always comfortable with language that implies I've got a monopoly on the truth, or that my faith is automatically transferable to others.

Families across America are feeling the pinch as they watch debts mount, bills pile up and savings disappear.

Is this money well spent? This is taxpayer money, it is going to be adding to the deficit short term and if we can't justify it, then we're not going to spend tens or hundreds of billions of dollars, just to make somebody happy, if it's not good for the economy.

What I remember thinking at that point, having gone through both the ups and downs of my first four years, and seeing the sea of people was, "What a remarkable country this is and how lucky am I that we live in a place where the son of a single mom, not born into any kind of fame or fortune, in a pretty remote state somehow can end up be in a position to - to make a difference."

When you see a Donald Trump and a Bernie Sanders, very unconventional candidates, have considerable success, then obviously there's something there that's being tapped into; a suspicion on globalization, a desire to reign in it's excesses, a suspicion of elites and governing institutions that people feel may not be responsive to their immediate needs. And that sometimes gets wrapped up in issues of ethnic identify or religious identity or cultural identity, and that can be a volatile mix.