It's well-known that the Army might not have enough combat troops to conduct sustained counterinsurgency campaigns. Now it seems the problem may soon be about quality as well as quantity (brains as well as boots).

The main reason for the decline in standards is the war in Iraq and its onerous "operations tempo"—soldiers going back for third and fourth tours of duty, with no end in sight. This is well understood among senior officers, and it's a major reason why several Army generals favor a faster withdrawal rate. They worry that fewer young men and women—and now it seems fewer smart young men and women—will sign up if doing so means a guaranteed assignment to Iraq. They worry that, if these trends continue, the Army itself will start to crumble.

So, there's a double spiral in effect. The war keeps more good soldiers from enlisting. The lack of good candidates compels the Army to recruit more bad candidates. The swelling ranks of ill-suited soldiers make it harder to fight these kinds of wars effectively.

Petraeus and officers who think like him are right: We're probably not going to be fighting on the ground, toe-to-toe and tank-to-tank, with the Russian, Chinese, or North Korean armies in the foreseeable future. Yet if the trends continue, our Army might be getting less and less skilled at the "small wars" we're more likely to fight.

So, we're facing two choices. Either we change the way we recruit soldiers (and, by the way, cash bonuses are already about as bountiful as they're going to get), or we change the way we conduct foreign policy—that is, we engage more actively in diplomacy or, if war is unavoidable, we form genuine coalitions to help fight it. Otherwise, unless our most dire and direct interests are at stake, we should forget about fighting at all.