All this week, at the Army War College in Carlisle, Pennsylvania, the Army is conducting the latest iteration of its annual wargame. In the fictional future of the game, set in 2020, 120 players will wage a two-front war in the two regions that have come to dominate US strategy, with one scenario set in the Middle East — which I’ll get to sit in on — and another in the Pacific — which is classified. In the real world of here and now, however, what’s at stake is how the largest but least glamorous of the four military services plays catch-up to the Air Force, the Navy, and the Marines in reinventing itself for the post-Afghanistan era.

The Army War College has hosted similar wargames every year since the 1990s, but this year is different, because the world has changed. US troops left Iraq last December and are drawing down, albeit slowly, in Afghanistan. At home, budgets are shrinking and the Army’s shrinking with them, slated to shed eight combat brigades and at least 87,000 troops between now and 2017 (or far more, much faster if sequestration happens). To thrash out the Army’s response, the service’s intellectual hub, the Training and Doctrine Command (TRADOC), has convened a whole series of conferences and seminars on the future of the service, collectively entitled “Unified Quest 2012,” which began in October and led up to this week’s wargame as the climactic event. Out of that months-long process emerged the key themes that the assembled players are wrestling with this week.

Above all other issues rises the Army’s role in projecting US power abroad. The administration’s strategic guidance, released in January, formally swore off “large-scale, prolonged stability operations,” the very kind of counterinsurgency that’s been the Army’s all-consuming mission since 2003. Now the chief strategic challenge is how to shape events abroad without having large forces already on the ground, whether through the subtle influence of a small cadre of advisors or a sudden surge of reinforcements in a crisis.

Advisor teams and other aspects of “building partnership capacity” are something the Army is on top of after years of working with the Afghans and Iraqis; the conventional forces of the “Big Army” are now adept in foreign partnerships that were once a marginalized mission reserved for the Special Forces. Rapidly deploying forces to a distant warzone where they must fight their way in against sophisticated opposition, however, is something the Army has hardly practiced since 2003.

The other services, meanwhile, have all already returned to that kind of power projection as their primary focus. The Marine Corps has been emphasizing its return to its sea-borne, swift-striking roots in amphibious expeditions. The Air Force and Navy have joined intellectual and political forces to advance the concept of “AirSea Battle,” aimed at cracking open the “anti-access / area denial” defenses of regional powers like Iran or even China. The strategic problem in many ways resembles that of the 1990s, when the Army War College’s annual wargames began and the Army’s leaders were increasingly fixated on rapid deployment overseas, but today’s problem is even tougher. Potential adversaries have access to an ever-proliferating arsenal of techniques to hinder US deployment into their regions and hamstring US operations on arrival, a so-called “hybrid threat” that blends low-tech weapons like roadside bombs, naval mines, and suicide bombs with high-tech ones like long-range guided missiles and cyber-warfare.

The Army’s own briefing for wargame participants highlights the linked problems of the “hybrid threat” and enemy “anti-access/area denial” strategies on the first page and returns to it repeatedly thereafter. It also explicitly raises the question of the Army’s role in the AirSea Battle construct, so far dominated by the Air Force and Navy. This isn’t only an Army wargame. Besides Army officers and civilians, the players include officers from the other US services, liaisons from foreign militaries, and representatives from a range of civilian agencies. Most of the participants will play as members of the simulated American command, but about one in nine will represent the neutrals that the US must sway or the adversaries it must defeat. Later in the week, another 60 or so senior officers and outside experts will convene to address the high-level strategic issues raised by the two theater-level games. Friday will see the final briefing to Army senior leaders. The final formal product will be a revision of the Army’s “Capstone Concept” later this year, but the larger issue is the Army’s struggle to assert its strategic relevance in the post-Afghanistan era.