We face now an era where we're going to be fighting the terrorist threat. I mean, that's simply a reality we are going to have to address that one.

I'm from the American West. We have forest fires out there. And some of the worst forest fires in our history, the most damage were caused when we pulled the fire crews off the line too early. And so we're going to have to continue to keep the pressure on the enemy - ISIS. There's no room for complacency on this.

We do everything humanly possible, consistent with military necessity, taking many chances to avoid civilian casualties, at all costs.

What concerned me was that [James Mattis] played not only a critical role as a battlefield commander in Fallujah, but also, afterwards, when he was promoted to various other higher-ranking positions, he served as a convening authority in court-martial proceedings against various marines who had been accused of atrocities - for example, in the Haditha massacre, where a group of marines went on a killing spree after one in their unit was killed.

For the mission's sake, our country's sake, and the sake of the men who carried the Division's colors in the past battles - who fought for life and never lost their nerve - carry out your mission and keep your honor clean. Demonstrate to the world there is "No Better Friend, No Worse Enemy" than a U.S. Marine.

Since 9/11 we've been engaged in wars around the world, and General [James] Mattis has been a leading battlefield commander in many of those theaters, including in the April 2004 siege of Fallujah, where the US Marines killed so many people that the municipal soccer stadium in the city had to be turned into a graveyard for the dead.

Be polite, be professional, but have a plan to kill everyone you meet.