December 16, 2009 ABC NIGHTLINE

GIBSON: I've always been fascinated by this question of -- of what it takes and what you have to go through internally to send kids off, as you said a few moments -- when you were in the Nobel speech, you said some will kill and some will be killed.

OBAMA: Right.

GIBSON: It's an enormous responsibility. And before Gulf War I, I went to Kuwait, and I talked to the commanders, Army, Navy, Marines, Air Force, and I asked them, what does it feel like to commit kids to war? And they all said, "We don't. The president does. It's his job. We just carry out his order."

OBAMA: Right.

GIBSON: And I thought, "Holy God, what a weight that is on your shoulders."

OBAMA: It is tough. And, you know, probably the most powerful moment of my year was when I traveled up to Dover and not only met with the families who were there in the middle of the night waiting for their loved ones to come home in caskets, but walking up the ramp of the transport plane by myself and seeing those caskets, it's -- it's -- it's indescribable, and it reminds you of the extraordinary courage and sacrifice that these young men and women are willing to make, but it also reminds you that you have the solemn obligation to make the best possible decision that you can make and that there is an element of tragedy involved in war that is inevitable, and that was the topic of what I spoke about last week. And if you don't understand that, if you think that this is all chest-beating and glory, then you're probably not making the best decision as possible.

GIBSON: As you went through that assessment in recent weeks, is there a calculus in your mind? Do you have to go through it? What is this worth in terms of human life?

OBAMA: Yes.

GIBSON: Is this goal worth 500 lives, 1,000 lives, 1,500 lives? Does that go through your head?

OBAMA: I don't think that you make a decision trying to weigh the value of 1 or 10 or 100 lives, because every life is precious. I think you make decisions based on an assessment of America's national security, the potential for additional lives, thousands of lives potentially being lost if we're not making the right decisions that preserve that national security.

What you want to make sure of is that, in these decisions, you are not making them based on abstractions, notions of, you know, of a battalion here or a battalion there, a brigade here, a brigade there, without understanding that in each of those battalions, in each of those brigades, there are young men and women with their lives ahead of them who you are committing.

And so that is a constant ballast, I think, to making the best possible decisions. But, look, part of the decision I have to make is also what is the absolute best way for us to prevent another 9/11 from happening. What is you know, how do we make sure that we're not in a situation in which a major American city is threatened?

So all these things go into the calculus. In the end, the best you can do is make sure that you've heard every opinion, that you have evaluated and analyzed every aspect of your decision, that you have clarity about what your choices are, understanding that the choices that you have are very rarely the ideal choice versus a terrible choice, but rather a range of choices, all of which have problems with them. From ABC News