Expanding American ground forces is necessary if one or both of two things are true. First is if the United States will need to sustain a major military presence in Iraq and Afghanistan for an extended period of time. If so, we need a larger Army and Marine Corps to increase the interval between deployments, thus protecting the quality of life for service members and providing time for training and professional development. Certainly Iraq and Afghanistan badly stress the Army and the Marine Corps. This must be addressed before American land forces irreparable damage. But enlarging the ground forces may not be the best way to do this. It will be years before an expanded force produces more noncommissioned, company and field grade officers—the groups most affected by the current pace of deployment. New units will need leaders, thus increasing the demand for noncommissioned, company and field grade officers even more. (my emphasis)

Expanding the military also makes sense if its mission is to undertake future operations like Iraq and Afghanistan—large scale, protracted counterinsurgency support and stabilization activities. This is the main rationale for expansion. But should in be? A powerful case can be made that outside the Western Hemisphere, the strategic and economic costs of U.S. involvement in large scale, protracted counterinsurgency or stabilization outweigh the benefits.

Supporters of expansion often contend that the United States must undertake counterinsurgency or stabilization because “ungoverned spaces” provide a breeding ground or haven for transnational terrorists. This is an unsubstantiated assumption. Al Qaeda did not operate in Afghanistan because that nation was ungoverned. Al Qaeda has training facilities in Pakistan because the Islamabad government elects to leave alone. Even if the U.S. Army and Marine Corps were double their current size, this would not change. We certainly face a strategic problem in Pakistan, but expanding the U.S. military is not the cure.

Even if an insurgent movement won, it would be more effective to prevent it from providing a haven to al Qaeda after it seized power than to try and prevent it from seizing power in the first place. We can coerce or remove regimes which support terrorism. We are good at it. We are not so good at the much more complex, dangerous, and expensive task of re-engineered beleaguered partners, particularly if we must do it in several places at once. Yet if we have a larger ground force, we will feel compelled to use it, undertaking costly commitments. Better to resist in the first place than to stumble into massive burdens for limited strategic gains.