The current debate over Iraq, including the surge and new counterinsurgency strategy, is really a proxy for a larger contentious struggle within the Pentagon over future war planning: the mix of weapons and major platforms we buy and the way we organize the troops.
On one side are those who argue that Iraq is "ruining" the force, making it unprepared for major wars. On the other side are those who see Iraq as harbinger for a far messier global landscape.
Americans should pay attention to this larger debate because our nation's military capabilities determine the possibilities of its foreign policy and grand strategy.
As the owner of the world's biggest gun, the United States can view international affairs from a perspective afforded no other nation. Conversely, we're viewed by the world very differently because of that capability.
Each of our nation's four military services wants to remain as "full service" as possible, meaning able to fight wars both big and small. During the Cold War, that sort of redundancy made sense, but now military think tanks are increasingly arguing, as in a recent RAND report, for a clear division of labor.
Since air power defines modern war, the argument goes like this: Let the Air Force and carrier-centric Navy focus on responding to major war threats, like North Korea, Iran and China; and let the Army, Marines and Special Operations forces focus on counter-terror, post-conflict stability and counterinsurgency operations.
So we're talking a technology-intensive big war force complimented by a manpower-intensive small-war force.
The big shift here is between the Army and Navy, and both sides feel plenty of angst.
For the vast bulk of its history, the Navy, in combination with the Marines, has been that "everything else" force: Until World War II, America had a Department of War (Army) and a Department of Navy.
During the Cold War, the Navy became fixated on the Soviet threat like every other service, and submarine commanders dominated its leadership.
After the Cold War, the Navy and Marines made a doctrinal bid to manage the world. In a mini-me version of the Powell Doctrine, they promised to deal with smaller crises, leaving the Air Force and Army to worry about big wars.
But that combination proved insufficient across the 1990s, and once the global war on terror kicked in and America quickly became saddled with two long-term nation-building exercises, it became clear that the Army was looking at a back-to-the-future transformation.
By that I mean the Army returns to what it did prior to World War I, serving as the nation's primary constabulary/frontier integrating force. Think back to the post-Civil War Army "departments" in the trans-Mississippi West - basically forerunners to today's worldwide system of regional combatant commands.
Their jobs should seem familiar enough to today's troops serving in Iraq and Afghanistan: protecting supply lines, enabling the construction of key infrastructure and fighting stubborn insurgencies.
That frontier-integrating focus ended with World War I, when the U.S. Army cavalry regiments, sized below 5,000 troops, were rolled up into giant 20,000-plus-man divisions so the force would be symmetrically arranged for the great war ahead.
The Army kept that force structure until Iraq, when incoming Army Chief of Staff General Peter Schoomaker broke all those divisions back down to regiment-sized "brigade combat teams" of 4,000-5,000 troops, each structured to act as independent units just as the divisions had been.
But here's the rub that connects these two debates: Many senior civilian officials and military officers fear ground forces will lose out in budgetary battles on big-ticket weapons systems and thus be left vulnerable to a shift in public opinion toward nonintervention in future small wars and civil strife abroad.
In short, the big-war Air Force and Navy will clean up while the Army and Marines, plus the reserve component, get used up in Iraq and Afghanistan.
This is the essential strategic choice America faces today: pulling back from a messy world to plan for brilliant, high-tech wars against major opponents or sticking with the effort in places like Afghanistan and Iraq.
By sensibly splitting the difference with a division of labor among the services, both tasks can be adequately served.
But don't expect the ground services to accept this outcome without a struggle. Old Cold War habits die hard, and inter-service budget rivalries die harder.