"Nor do we gain any satisfaction from the accuracy of our prediction. Because the consequence is a price that our people have paid in blood. During 19 Brigade's tour so far they have lost 55 soldiers on operations, and many others have been wounded, some very seriously.
"Each death is a tragedy that has left bereaved and grieving families and friends; some of the injuries have changed people's lives for ever. As a military, we know that our job involves risk, and that in conflict we will suffer losses. It is not something one ever gets used to, but it is something one learns to deal with. At the same time, though, we have constantly to ask ourselves whether we are gaining sufficient strategic benefit to justify the price our people are paying. This is not, and never can be, a simple calculus. How do you weigh a human life in the balance against an intangible? But it is a judgement we have to make.
"Some will always be opposed to military action; I understand and respect that, although not unnaturally I take a very different view. Most, though, will accept the logic of military involvement on the international scene, provided it can be justified. And in the context of Afghanistan, it seems to me that we have to be able to answer three basic questions.
"First: is it worth it? Is the situation in Afghanistan of sufficient importance to the UK's strategic interests to justify the commitment and the cost? Secondly: is it doable? Even if the issue is of strategic importance, is what we are seeking to achieve actually within the realm of the possible? And finally: are we doing it properly? If we are able to convince on the first two questions, we still need to demonstrate that we can make and are making the mental and physical commitment necessary for success.
"There has been much debate about the rationale for our engagement in Afghanistan. I see it in fairly straightforward terms. We face extremist Islamist groups who pursue a campaign of global terrorist violence in order to further their ideological ends. These groups pose a direct threat to the UK, its citizens and their interests, so must be countered.
"But we cannot counter them effectively by taking them on one-by-one. We have to help foster an environment in which it is much harder for them to thrive and operate. And as part of that effort, we need to reduce the ungoverned spaces which harbour such groups, and from which they mount their campaigns.
"One such area - of critical importance to us - straddles the border between Afghanistan and Pakistan. Our objective there is to help the governments of both those countries extend effective governance to parts of their population that have been without it for far too long, in order to reduce the effectiveness of Islamist terrorist groups that pose a direct threat to the UK. So Afghanistan is an issue of strategic importance for us, of immediate relevance to our own security.