The problem that the US faces with every act of warfare we undertake, is that our country doesn't do so for to conquer or claim land or resources. Why is that a problem? To maintain peace after a war, the winning side must occupy the conquered people's land and impose the rule of law and put down any reactionary uprisings. We did this in Germany, Japan, Italy, and South Korea. Although we have not claimed the right of annexation of any lands we occupied since the Spanish-American War in 1898, we have until recently imposed our will over the conquered people and their lands. In fact, we still have armies in Germany, Japan, South Korea, and even Italy although they are a little different because they turned on the Germans and became a quasi-ally after our invasion of Italy during WWII. Our post-WWII/Korean War doctrine worked - sort of an "Occupation Light" version of ruling a conquered people. In fact, it worked so well that government officials that followed during the era of Vietnam, Iraq 1993, and so on, felt that we could even go even lighter. That's where we failed.
In Iraq, both times, we did neither - impose the rule of law or leave an occupying force. We set of on a new version of foreign policy, a new version of the Marshall Plan called "Nation Building" but without the occupying force, without the imposition of outside force to impose the rule of law, and a policy which did exactly the opposite of what the name (nation building) implies.
You are correct in your post that the US going to war "should only be done when faced with the most dire circumstances" which includes the dire circumstances which are invariably faced when the war is over which will require the US to do what modern US citizens may not like or agree with - occupation and imposition of the rule of law until the local government can maintain security and then keeping a security force in country for decades, maybe for generations.
War is ugly, and so is the recovery process required after the fact. A war cannot be prosecuted half-ass with any reasonable expectation of success, nor can the post-war recover be undertaken in a half-ass, let's get the hell out as soon as possible, no more boots on the ground neglecting of our duty to help the people we conquered to rise back up and re-enter the world of peaceful nations.
