'Duty' is a refreshingly honest memoir and a moving one. Mr. Gates scrupulously identifies his flaws and mistakes: He waited too long, for example, for the military bureaucracy to fix critical supply issues like the drones needed in Iraq and took three years to replace a dysfunctional command structure in Afghanistan.

Most people who aspire to be president don't have a foreign policy and national security background. The exception was certainly Hillary Clinton.

Russia, their number one client in the Middle East is Syria; that is their foothold in the Middle East. They want to have influence there.

The fact that we walked away from the Middle East, as distasteful as it was for us to stay involved and prevent wars, based on our long involvement there, we have helped to create and provide a foundation. Obviously for ISIS and also for the absolute barbarianism and human catastrophe that Assad impacted on his people.

I totally disagree with the premise that al Qaeda is on the path to defeat. Quite the contrary, al Qaeda has deliberately decentralized its operations - not because of the relentless attacks we have had on its national leadership in Pakistan, but because its strategic objective is to dominate and control Muslim countries in the region.

ISIS is at war with America, but America is not at war with ISIS - not the president, nor the Congress, and certainly not the American people.

We have a sufficient political class, and the military doesn't have to get involved in high national office. The days of doing that, post-Civil War and post-World War II, are gone.

In 2011, General Alston, four-star commander in Iraq, recommended to the President, a force level of over 20,000. The President rejected it and pulled out all the forces with what is now known as a disastrous consequence in Syria.

If you're going to maintain true authorities over a subordinate organization, you have to have some control over policy formulation of that organization and also the resources that are applied to it.

Economically, ISIS is making money every day on the black market with their oil fields. But they are also putting money in banks. We know where those banks are. We should go after the banks and the facilitators using them.

What did we want out of Iraq? We wanted a country that was stable and secure, that elected its own government, that was not going to be a threat to its neighbors and also was capable of protecting and defending itself. That was our objective in Iraq.

While conducting a conventional war in Iraq and Syria, ISIS has staged terrorist attacks on a global scale against the people from the countries who are fighting ISIS.

The fact to the matter is, we never developed a comprehensive strategy to deal with radical Islam. And the 9/11 commission said one of the things we must do is develop a global alliance to combat it.