A number of countries, including some who have loudly criticized the NSA, privately acknowledge that America has special responsibilities as the world's only superpower, that our intelligence capabilities are critical to meeting these responsibilities, and that they themselves have relied on the information we obtain to protect their own people.

With only 2 percent of the world's oil reserves, oil isn't enough. This country needs an all-out, all-of-the-above strategy that develops every available source of American energy. A strategy that's cleaner, cheaper, and full of new jobs.

As part of the coalition against ISIL, we are putting that terrorist network under tremendous pressure.

A low-carbon, clean energy economy can be an engine of growth for decades to come.

You have to have a strong team around you [being a president].

We know we can't stop every act of violence, every act of evil in the world, but maybe we could try to stop one act of evil, one act of violence.

The president does not have power under the Constitution to unilaterally authorize a military attack in a situation that does not involve stopping an actual or imminent threat to the nation. As commander in chief, the president does have a duty to protect and defend the United States. In instances of self-defense, the president would be within his constitutional authority to act before advising Congress or seeking its consent.