Mattis has been sharply critical of President Barack Obama's policies on Iran and Obama's capping of troop numbers and campaign end-dates in theaters of war such as Afghanistan and Iraq. Mattis also appears to be a skeptic of the Obama-era policy of putting women into combat roles.

The senior director at the NSC for the Middle East is retired Col. Derek Harvey, an Arabic-speaking intelligence officer with a Ph.D. who served as the head of the U.S. military cell examining the insurgency in Iraq in 2003.

An intelligence officer and historian, Rayburn published a 2014 book, 'Iraq After America,' which is a must-read for anyone who wants to understand how Iraq descended into chaos in the years after the American troop withdrawal at the end of 2011.

The hard reality is that attacks by vehicles in public places are very hard to defend against in a free and open society. The best defense against such attacks is good intelligence, and that often comes from inside the Muslim community.

Contemplation of life after retirement and life after death can help you deal with contemporary challenges.

Death became a desired option. I hoped I would hit a mine or run into an ambush and just end it all. I think some part of me wanted to join the legions of the dead, whom I had failed.

I think I'm a survivor. I could have suffered at least 100 professional deaths. I could come up with a list of the 100 times I've come closest to death, from having pneumonia as a child to car crashes.

Prepare for death, if here at night you roam, and sign your will before you sup from home.