I don`t think the Donald Trump`s qualified to be president of the United States, and every time he speaks, that opinion is confirmed.

In a world of complex threats, our security and leadership depends on all elements of our power - including strong and principled diplomacy.

The path towards sustainable energy sources will be long and sometimes difficult. But America cannot resist this transition, we must lead it.

Moammar Gadhafi had more American blood on his hands than any individual other than Osama bin Laden.

Nothing can stand in the way of the power of millions of voices calling for change.

How you staff, particularly the chief of staff, the national security adviser, your White House counsel, how you set up a process in the system to surface information and generate options for a president, understanding that ultimately the president is going to be the final decision-maker. That's something that has to be attended to right away.

I've said to [Donald Trump], and I think others have said to him that the day that he is the President of the United States, there are world capitals and financial markets and people all around the world who take really seriously what he says, and in a way that's just not true before you're actually sworn in as president.