To resolve this issue will require Iran to come to the table and discuss in a clear and forthright way how to prove to the international community that the intentions of their nuclear program are peaceful. [...] The question is going to be whether in these discussions they show themselves moving clearly in that direction.

I don't want to make promises, not knowing what the situation's going to be three or four years out.

One of the thing about being President - that can't be taught, you have to experience, is - there is the sheer weight of decision making. And when I make a decision to send 17,000 young Americans to Afghanistan - you can understand that intellectually. But understanding what that means for those families, for those young people - when you end up sitting at your desk, signing - a condolence letter to one of the family members of a fallen hero - you're reminded each and every day, at every moment, that - the decisions you make count.

Get informed, not by reading The Huffington Post.

The changes in thinking about same-sex marriage have come slowly at first and then in rapid course. If such change is possible in this area, is it also possible in the vexed and sordid realm of race relations?

Climate change constitutes a serious threat to global security.

I think what will happen with Donald Trump is there are going to be certain elements of his temperament that will not serve him well unless he recognizes them and corrects them.