A country that armed Stalin to defeat Hitler can certainly work alongside enemies of al-Qaida to defeat al-Qaida.

General [James] Mattis's primary experience - indeed, his only experience - is as a member of the United States Marine Corps, where he served for 41 years. That's his experience.

We have the most skillful, firecest, and certainly the most ethical ground forces in the world... I'm not saying we have to commit right now, but certainly don't pull it off the table.

I just hope we can find our way back to engaging with one another, arguing strongly with one another, and then going down and having a root beer together or something and - and having a good laugh about it as we work together for the best interests of the next generation of Americans who are going to inherit this country.

ISIS is a threat to all civilized nations. America's intention is that the foreign fighters do not survive the fight to return home to North Africa, to Europe, to America, to Asia, to Africa. We're not going to allow them to do so. We're going to stop them there and take apart the caliphate.

You can overcome wrong technology. Your people have the initiative, they see the problem, no big deal ... you can't overcome bad culture. You've gotta change whoever is in charge.

You are part of the world's most feared and trusted force. Engage your brain before you engage your weapon.