More emphasis will be put on peacekeeping and dealing with messy political conflicts. Are preemptive strikes dead?
Years from now, when today's lieutenants and ensigns are generals and admirals, what will make them nervous? That is, what will be the "Vietnam syndrome" equivalent applied to those in uniform today, battlefield experiences they had that raise warning flags when they're asked to fight again?
That will be one very pointed way of considering whether the lessons of US operations in Iraq have been learned. With the symbolic handover of Iraq to Iraqis this week, that examination of US military doctrine and tactics there officially begins.
But like Vietnam and World War II, such lessons aren't confined to Pentagon planners and service academy professors. They are inevitably connected to how political leaders and Americans generally - those who send service men and women into harm's way - see the role of the United States in the world.
Among the questions raised by a war that has been longer and costlier than anticipated: What kind of future conflicts should be expected and prepared for? How will the makeup and placement of US forces around the world change? And perhaps most important to those who do the nation's fighting: What's the outlook for shoot-first "preventive war" as advocated by neoconservatives prominently advising the president?
Much of the discussion revolves around the so-called Powell Doctrine of war (explicit objectives, overwhelming use of force, clear exit strategy) versus the "Rumsfeld Doctrine" (smaller numbers of highly maneuverable ground forces, emphasis on special operations, and high-tech air power).
At this point, there are more questions than answers. But a few things are certain.
"Marines and Army will resemble each other more and more - light, mobile, transportable," says retired Army Col. Daniel Smith, military affairs analyst at the Friends Committee on National Legislation in Washington. "Heavy armor will be downplayed. Heavy artillery will be downsized. Special operations units - SEALs, Air Force special ops, Green Berets, Delta [forces] will be larger and more active."