This is not to say that war is a good thing, just that it seems to have been a fact of life from time to time for a long time. There is an element in the United States that seems us to not ever win a war, maybe to be fair, so that we won't fight any more wars, and so a war that was perceived as ending somewhat badly would be the end of war for us, and in certain extreme Socialist circles, a small set of whom want actual defeat, such a defeat would be the end of war period, since we are inevitably at fault for all wars.
As to that granted very small minority view, and note CCR had a line in the sixties worth remembering about the opposite problem of the extremes of the other side on the "Right"
("Some folks are born made to wave the flag,
Ooh, they're red, white and blue.
And when the band plays "Hail to the chief",
Ooh, they point the cannon at you, Lord,)
some even try to blame the United States for our version of the Korean War, and would if there were another one starting shortly.
Hopefully, that won't come to pass, although demonstrating resolve to fight a war in Korea should it be necessary is a matter of grave importance to American security, since Korea is the only place American troops have easy access to Mainland China, save for Afghanistan.
We can cross the Yellow Sea at the Shanhuiguan pass, move to Beijing, and burn it to the ground as has been done on numerous occasions, without initiating the use of tactical or strategic nuclear weapons.
If we have to fight a war with China some day, either we are using all air, with a risk of being perceived of using nuclear weapons, or then cyber attacks no one has any expericence as to civilian dislocation, and possibly in either instance generating a use it or lose it scenario in them losing C4RSI and then having to strike their nuclear weapons first, or, we have to get there on the ground.
Since we left Vietnam, that means Korea or Central Asia, and depending on Pakistan in the latter scenario, if Okinawa and Taiwan are also potential jumping off places, as is Burma, and of course, we wouldn't be the party starting a war, but merely finishing it on favorable terms.
One would think that is a worst case scenario, although since such scenarios in fact exist as to the implications of a crisis over Taiwan, then one has to plan, which generates a certain logic of its own, such as things are in this world.
As to the question of the laws of war and Afghanistan, much has been made of the speech by John Brennan as to civilian casualties.
Although you never want to kill civilians intentionally, it always happens too, something to think about before launching wars very seriously.
It is also illegal to kill civilians deliberately under international law, although if one exercises care in military operations, it has always been accepted that innocent people die.
Then there remains the legal question of proportionality" "Was the killing reasonably related to a target that was a legitimate object of military action?"
Clearly, people waging war against American interests overseas, like Al Qaida, or waging war against an ally like the Karzai government, are normal targets of war in the grand scheme of things.
The question then becomes "Are we taking steps to keep civilian casualites low enough to be defensible under the laws of war?
Then so long as that is true, one is operating under current international law, which does not allow for selective vaporization of say Pakistani villages that everyone knows have been a problem for a long time, as a message: "Not any more? Do something else for a living, entertainment, and general sense of identity, or you will die."
Some in the old school still think that has a place, but they don't really do that any more, or you would know it.
You would know it, because for all the slanders about American war crimes as a general rule that actually are dangerous as to making some overseas think we aren't united in national defense, at least at some point, even if the Right does launch wars too much, obviously, then you would see B-52 strikes on villages that can vaporize an area two by four kilometers. Everything in a 27 B-52 raidwithin two by four kilometers in the 3 by 9 formation is exposed to 15 pounds blast overpressure, and therefore is killed, deafened,maimed and/or rendered combat ineffective.
Since we have that capability, and you haven't heard of that happening, you know we aren't deliberately trying to maximize the number of civilian deaths in the conflict in Afghanistan, and so aren't war criminals, unlike some Russian high altitude bombing towards the end of their engagement, even as some think taking even the remote possibility of a limited set of such strikes off the table has serious risks as to demonstrating commitment to victory or death, like the enemy.