Mackubin Thomas Owens, writing for The Wall Street Journal, argues that our military must not foreclose policy options for our leaders by its force structure decisions. He points out times in the last 50 years when it has done just that, with negative consequences.
Basically, the argument is between those who see the future dotted with insurgencies and asymmetrical warfare, calling for a military that is as much constabulary as it is army; and those who see the real threats coming from more traditional interstate warfare between real armies with heavy armor and artillery components and a real line of battle.
Owens, who teaches at the Naval War College, believes that we must maintain high level abilities to fight both kinds of conflict. Given the human propensity to kill each other, at both the wholesale and retail levels, he is very likely right.