In military planning, going somewhere and breaking things is relatively easy to plan. Getting out of there is another thing entirely.
We still have troops in Germany, Japan, and Korea. They are stable democracies (now) that are valued trade partners (now). Meanwhile Central and South America have been SOCOM playgrounds for the last few decades, and with the exception of Hugo "I smell sulfur" Chavez, relatively good trade partners.
We went into WWII without an exit strategy, and turned Germany into ground zero for the conventional Cold War. We went into Korea without an exit strategy and ended up playing "who blinks first" with the Norks for six decades. We went into Japan without an exit strategy and ended up installing a military governor.
What sort of nation acts that way? To conscript their citizens and send them to occupy foreign lands? Empires. And all empires fall. And all empires have an Emperor.
If I were emperor, my policy would be thus. We don't go to war with anyone not worth occupying. That means an industrious people with a solid grasp of literacy and mathematics. It is easy to work with the Japanese or Germans. Or even Indians (God bless their continually occupied hearts).
Vietnam? Who really cares if some jerkwater nation on the backside of nowhere falls to communism? It only means that the jerkwater nation beat us to our endpoint by a few decades. Kuwait on the other hand, invade, save that valued trade partner!
The true value of a nation is not in a particular resource, but in people willing to turn resource into wealth and engage in trade. I wouldn't wage war based on "keeping people free" or any altruistic goal. I would wage war on building a profitable peace to follow.
Slowly but surely the world would be made better, as our trading partners prospered, and those who didn't trade didn't prosper (that is the other side of the foreign policy gambit). You don't have to go to war with a country to wreck their economy. If only I were Emperor. Then again, I'm sure my domestic policies would be a proper mess.