I'll overlook the gratuitous crack about "unilateral disarmament" and stay focused on what's important. There are three main points to consider:

When you're attacked, you fight back with all you've got, without regard to cost.

In all other situations, war is a discretionary choice, and it's only smart to weigh the cost versus the expected benefits, and to compare the cost of war to the cost of alternatives.

Bush introduced a dishonest and cowardly hybrid with his doctrine of preemptive warfare. It's discretionary war hiding behind the imperative of the imagined prospect of attack. No matter how you spin it, it's still discretionary, because before the anticipated attack comes, you always have time to consider more options than war...if you don't panic. To pretend otherwise, as Bush does consistently, and ignore options such as diplomacy and sub-violent options such as embargo and international pressure, is horribly irresponsible, and thoroughly strips away the pretense of defensive action. We were the aggressor in Iraq, pure and simple.

In a cost-benefit analysis of the choice to go to war, it's wise to discount the promised benefits against the historical experience of the last century. At the moment I can't think of any war in the 20th Century that was won by the aggressor. Maybe somebody can dig up a small brush war that succeeded, and identifying the aggressor is impossible in civil wars; but the fact is, aggression has a very poor track record of success. Kaiser Wilhelm, Hitler, Mussolini, and Tojo got their asses kicked, Saddam Hussein got his ass kicked in Kuwait, the Soviets had theirs handed to them on a platter in Afghanistan, and so did we and the French in Vietnam. BTW, in regard to the latter, I'd have to categorize choosing to intervene on one side in a civil war as a choice that effectively makes the intervenor the aggressor.

The reason why aggression fails so often goes back to point #1 and it's braindead simple: The nation you attack is willing to throw everything it has into the battle, while the aggressor must consider the cost. Aggression games out as a very undesirable strategy.

How the neocons could imagine that they could make aggression work against all experience is absolutely beyond me.

It's clear that a good defense always works better than offense. We chose not to attack the Soviet Union during the Cold War, and concentrated on a strong defense, including deterrence through the prospect of retaliation; and on smaller-scale maneuvering through proxies at times, more often through diplomacy and economic pressure. We won that way.

Peace comes through strength, respect, and a little fear on the part of those who would harm us.

Each of those ingredients could be interpreted offensively or defensively, and it's my thesis that only the defensive interpretation has any real power. Strength to be ready to fight back and win, mutual respect to diminish the reasons for war in the first place, and fear on the part of potential aggressors of what will happen if they "awaken the sleeping giant", as the Japanese discovered to their ruin.

So of course I agree with Horace that "a wise man in times of peace prepares for war". Not for the purposes of initiating war, but to deter it. I disagree with Tacitus's implied objective, because I think that pursuit of an American empire is a really bad idea. Why in the world would we want responsibility for all those idiots out there? But all the rest is simply common sense.

Let me add a fourth ingredient: Perception. If you don't initiate war, your strength remains a matter of potential, and you can get a lot of mileage out of building up your image as invincible at relatively little cost. The Soviets ran that trip on us pretty effectively during the Cold War, and only later did we learn what a hollow threat they really were.

But if you do start a war, you immediately lose the advantage of perceptions, and the world gets a very precise calibration of your actual strength. Once that happens, deterrence becomes more expensive, because it must all be real and can no longer be inflated.

Bottom line: A nation has everything to lose and little to gain by aggression. Peace isn't just the morally preferable option, it's the smart option.