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.

I think Putin wants to recreate as much of the Soviet Union as he can through a variety of different means. He's invaded parts of Georgia, took Crimea, southeastern Ukraine, bases in other countries.

In Afghanistan you are not rebuilding, you are building. There is very limited infrastructure and extreme terrain, with deserts in the south and mountains so high in some areas that helicopters don't even fly well at a certain altitude because the air becomes so thin. The country has a serious problem of illiteracy, especially after so many years of war and Taliban rule.

I did a week-long assessment in 2005 at (then Defense Secretary Donald) Rumsfeld's request. Following our return, I told him that Afghanistan was going to be the longest campaign of what we then termed "the long war."

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.

There has, indeed, been very substantial progress in Iraq over the past year - violence is down by 80 percent, civilian deaths by about the same, and so on.

The progress in Iraq is still fragile. And it could still be reversed. Iraq still faces innumerable challenges, and they will be evident during what will likely be a difficult process as the newly elected Council of Representatives selects the next prime minister, president, and speaker of the council.