The most important six inches on the battlefield is between your ears.

With respect to the outlines of what's in the Army Field Manual, there's no doubt in my mind about the limitations it places not only on the DOD, but on the Central Intelligence Agency. And I'll always comply with the law.

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.

When you're in operations, the best thing you can do at the top level is get the strategy right. You have to get the big ideas right, you have to determine what is the policy, what is the level of effort you're willing to commit to it? And then you delegate to those who have to execute that strategy to the appropriate level. What's the appropriate level? It's the level where people are trained and equipped to take decisions so we move swiftly against the enemy.

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

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.

You cannot allow any of your people to avoid the brutal facts. If they start living in a dream world, it's going to be bad.