I am not a politician, and I will never be, and I say that with absolute conviction.

The Islamic State fighters in Mosul are dead men walking and I think they increasingly know it.

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.

The art of coalition command - whether it is here in Afghanistan, whether it was in Iraq or in Bosnia or in Haiti - is to take the resources you are provided with, understand what the strengths and weaknesses are and to employ them to the best overall effect.

Don't forget Yemen, where there are also extremist elements, as we saw recently.

Let's remember that the reason we are there is that we have vital interests in Afghanistan, hugely important national interests, as do the other countries involved.

This cannot be the United States being the air force for Shia militias, or a Shia on Sunni Arab fight.