If you're asked, you've got to serve - put aside any reservations based on campaign rhetoric... and figure out what's best for the country.

A certain degree of intellectual humility is a good thing.

Leading the coalition military effort during the surge in Iraq in 2007 and 2008 was the most important endeavor - and greatest challenge - of my 37 years in uniform.

Like a nuclear disaster, the fallout from the meltdown of Syria threatens to be with us for decades, and the longer it is permitted to continue, the more severe the damage will be.

The bottom line is, you really have to commit to something if you're going to be successful in it.

Reconciliation is what takes place, of course, at higher levels. President Karzai has been very clear about the red lines for reconciliation, accept the constitution, lay down their weapons, cut their ties with al Qaeda and essentially become productive or at least participating members of society in that regard.

We're here so that Afghanistan does not once again become a sanctuary for transnational extremists the way it was when al-Qaeda planned the 9/11 attacks in the Kandahar area, conducted the initial training for the attackers in training camps in Afghanistan before they moved on to Germany and then to U.S. flight schools.

Every civilian's death diminishes us, collectively.

Iran has had a very harmful effect in a variety of ways in the region... fomenting unrest to a degree in Saudi Arabia, undoubtedly in Bahrain, and definitely in Yemen with Hamas, with Lebanese Hezbollah among other activities in locations.

The foremost threat to Iraq's long-term stability and the broader regional equilibrium is not the Islamic State, it is Shiite militias, many backed by - and some guided by - Iran.

The truth is that a number of us have been saying for quite some time that it was only a matter of time until someone went to a gun show, bought a military-like semi-automatic assault weapon with a large capacity magazine, and did enormous damage.

You cannot deal with an industrial-strength extremist problem just with force of arms. You have to have that political component as well.

The tragedy is that political leaders failed so badly at delivering what Iraqis clearly wanted - and for that, a great deal of responsibility lies with Prime Minister Maliki.

I've been in a position before where a president has turned to me in the Oval Office in a difficult moment, without any pleasantries, and said, 'I'm asking you as your president and Commander in Chief to take command of the international security force in Afghanistan.' The only response can be, 'Yes, Mr. President.'

Iraq is a country I came to know well and the place where I spent some of the most consequential years of my life.

The biggest of the big ideas that guided the strategy during the surge was explicit recognition that the most important terrain in the campaign in Iraq was the human terrain - the people - and our most important mission was to improve their security.

But clearly, this is what this is about. It's about pushing the security bubble out. It's about rooting out every last guy, so that there's not even somebody who can fire a single, solitary RPG round from some little qalat out here.

I refuse to use terms like 'optimist' or 'pessimist' and instead prefer 'realist.'

The situation in Iraq was dire at the end of 2006, when President George W. Bush decided to implement the surge and selected me to command it. Indeed, when I returned to Baghdad in early February 2007, I found the conditions there to be even worse than I had expected.

Folks really need to be very cautious about overanalyzing or overparsing what I've said to this reporter or that reporter.

Counter-insurgency, as you know, is a roller-coaster affair.

All Americans should take great pride in the men and women serving our nation in Iraq and in the courage, determination, resilience and initiative they demonstrate each and every day. It remains the greatest of honors to soldier with them.

Central to achieving progress in Afghanistan - and to setting the conditions necessary to transition security tasks from the international community to the Afghan government - is increasing the size and capability of ANSF.

Needless to say, it was the greatest of privileges to serve with the selfless men and women - Iraqi and American and those of our coalition partners, civilian as well as military - who did the hard, dangerous work of the surge. There seldom was an easy period; each day was tough.

It wasn't just Shia that would go to Tehran and see the commander of the Quds Force and others and the legitimate government leaders. It was also Kurdish leaders and Sunni Arabs who would even link up with Qassim Suleimani, the commander of the Quds Force - maybe not in Tehran but in Turkey or somewhere else.

The formulation of sound national policy requires finding the right overarching concepts.

You have to keep on disrupting. If you let up the pressure, then al-Qaeda senior leadership will come back.

The proximate cause of Iraq's unraveling was the increasing authoritarian, sectarian, and corrupt conduct of the Iraqi government and its leader after the departure of the last U.S. combat forces in 2011.

There aren't always a hell of a lot of absolutely right answers out there.

I'm heartened that, for the first time, we're seeing some of the Internet Service Providers and the social media sites taking action against the Islamic State. That's the kind of initiative that can very, very much augment on an industrial scale what the government is trying to do.

When I was commander of Central Command, obviously we were very concerned about the developments in Yemen, the developments in Somalia and elsewhere, in Africa and so forth. But the al Qaeda senior leadership is under unprecedented pressure.

We need to learn from our experiences and take responsibilities for our actions and drive on.

We all have to strive to learn what motivates us, learn from our experiences, and what feels right and what feels wrong. There's a strong component over the years to having formal processes that help to identify lessons that need to be learned, and actions that need to be taken. In other words, how do you find the big idea?

Well, the oil, the oil spot, if you will, is a, is a term in counterinsurgency literature that connotes a peaceful area, secure area. So what you're trying to do is to always extend that, to push that out.

President Obama has said that our aspirations should be realistic. We are not going to turn one of the poorest countries in the world, that was plunged into 30 years of war, into an advanced, industrialized, Western-style democracy. What we want to achieve is Afghanistan's capacity to secure and govern itself.

The Germans have done wonderful work. Not long ago, a German battle group battalion conducted a very impressive counterinsurgency operation in a portion of Baghlan province. I think these are the first counterinsurgency operations conducted by any German element after World War II. And they did a very impressive job.

People often ask, why aren't you reading about what it is you're working on right now? And the truth is, you only get three pages a night before your eyelids close.

During the surge in Iraq, we were able to roll back the tide of al-Qaeda and associated insurgents because we succeeded in mobilizing Iraqis - especially Sunni Arabs - to join us in fighting against the largely Sunni extremist networks in their midst.

The process to resolve post-Islamic State issues will be difficult and intense.

Partners from the Islamic world are of particular importance. Indeed, they have huge incentives to be involved, as the ongoing struggles are generally not clashes between civilizations. Rather, what we are seeing is more accurately a clash within a civilization: that of the Islamic world.

There were very few people who were both intercollegiate athletes and Star Men.

In all of our efforts, we continue to emphasize the importance of inclusivity and transparency on the part of the Afghan government and leadership, especially in linking nascent local governing institutions to the decision-making and financial resources in Kabul.

Needless to say, innumerable challenges exist in all areas of governance, and much more needs to be done to help the Afghan government assume full responsibility for addressing the concerns of ordinary Afghan citizens.

The Congress, the executive branch, and our fellow citizens have done an enormous amount to support our troopers and their loved ones. And all of us are grateful for that.

Nothing means more to those in harm's way than the knowledge that their country appreciates their sacrifices and those of their families.

Over time, the desire of Iraqis to contribute to their own security has manifested itself in citizens volunteering for the police, the Army, and concerned local citizen programs.

Proud parents document the arrival and growth of their future CIA officer in all forms of social media that the world can access for decades to come.

Beyond Iraq, I am also profoundly worried about the continuing meltdown of Syria, which is a geopolitical Chernobyl. Until it is capped, it is going to continue to spew radioactive instability and extremist ideology over the entire region.

There is not a military commander alive today who is genetically predisposed to say that he has enough ISR and assets, and particularly not in the Central Command theater.

Iraq does have many, many different tensions.