Fighting in cities is a totally different endeavor than obviously fighting out in the open.

I am neither a pessimist nor an optimist. I am a realist, and the reality in Iraq is that it has been very hard and it continues to be hard.

I will not ever run for political office, I can assure you of that.

There are some ideas that will translate from Iraq to Afghanistan and there are many that will not. The first lesson of counterinsurgency, in fact, is that every situation is truly unique, has its own context, its own specific set of factors - and you have to understand that context in enormous detail to be able to craft a sound and comprehensive approach.

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.

US Ambassador to Iraq Ryan Crocker and I have repeatedly sought to emphasize that the progress in Iraq is fragile and also, possibly, reversible.

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.