The American people and the American military will never get used to civilian casualties. And we will - we will fight against that every way we can possibly bring our intelligence and our tactics to bear. We're not the perfect guys, but we are the good guys.

I find it disturbing that no member of the Senate Armed Services Committee is willing to acknowledge that record of failure and to ask our next secretary of defense what he proposes to do to amend that sorry record.

In this age, I don't care how tactically or operationally brilliant you are, if you cannot create harmony - even vicious harmony - on the battlefield based on trust across service lines, across coalition and national lines, and across civilian/military lines, you need to go home, because your leadership is obsolete. We have got to have officers who can create harmony across all those lines.

What would you do differently as defense secretary to compensate for this record in which the greatest military in the world, as we are constantly told, doesn't get the job done?

I would consider the principal threats to start with Russia. And it would certainly include any nations that are looking to intimidate nations around their periphery, regional nations nearby them, whether it be with weapons of mass destruction or I would call it unusual, unorthodox means of intimidating them.

We are going to have to continue to keep the pressure on the enemy. There is no room for complacency on this.

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.