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.

The destruction that we have wreaked in the various theaters in which we've been engaged is really quite astonishing. But again, lethality, destruction, killing doesn't seem to achieve our objectives. So, my own sense is that a lack of lethality does not define the core problem.

Be the hunter, not the hunted: Never allow your unit to be caught with its guard down.

Yousef Aid Ahmed has memorized the places where his four brothers' bodies laid after they were killed by US marines, he said. The family recounts that November day in 2005 and says it was a massacre of the brothers, along with 20 other people, following a roadside bomb in Haditha.

In a country with millions of people & cars going everywhere, the enemy is going to get a car bomb out there once in a while.

I don't lose any sleep at night over the potential for failure. I cannot even spell the word.

Ultimately, a real understanding of history means that we face NOTHING new under the sun.