I’m sorry to be late to this party, but it’s really great to see Stephen Walt blogging for Foreign Policy magazine.  Walt is now clearly the most high-profile academic realist in the blogosphere, and it’s terrific he’s blogging.  A lot of people like to call themselves realists inside the Beltway, but they’re basically all liberals, in IR terms.  Actual realists have long been egregiously underrepresented in the American government, the American media, and basically everywhere in the U.S. outside the academy.  More people need to hear realist voices.  Realists wisely opposed the Iraq war, and have a host of ideas about how the world works that, if they gained greater sway in Washington, might help prevent the next couple of screw-ups the government is planning for us.

Here’s a good post from Walt on defense spending.  Walt writes that you’d think, since the United States enjoys a terribly benign threat environment, just elected a liberal Democrat president, and is facing an economic meltdown, the bloated defense budget ought to be on the chopping block:

Here’s why it won’t happen any time soon. As Cindy Williams, former director of the National Security division of the Congressional Budget Office and now a senior research scientist at MIT, points out in an as-yet unpublished paper for the Tobin Project, DOD is insulated from serious cuts by an array of impressive political advantages. First, its budget is more than 50 percent of all federal discretionary spending, and its sheer size gives it a lot of bureaucratic clout. Second, the Pentagon has a large domestic constituency: there are 1.4 million men and women in uniform, 850,000 paid members of the National Guard and Reserve, and 650,000 civilian employees. Forget GM, Ford and Chrysler: the Department of Defense is the largest single employer in the whole country. Now add the companies that provide goods and services for the military. Their employees amount to about 5.2 million jobs, which is a pretty impressive domestic constituency. And don’t forget those 25 million veterans, who are hardly shrinking violets when defense spending is concerned. Finally, a well-financed group of Beltway bandits and Washington think tanks stand ready to question the patriotism of any politician (and especially any Democrat) who tries to put the Pentagon on a diet.

Matt Yglesias responds to this with a note of surprise, and then an endorsement:

It seems unlike a realist to cite domestic political dynamics as the cause of national security policy, but clearly this is correct.

This is a pretty common objection when realists talk about foreign policy, as opposed to international politics, but it belies a misunderstanding of the theory.  Realists talk a lot about structure in the international political context: various structures of the balance of power push states in one direction or another.  If Mexico were twice as powerful as the United States, different structural forces would be acting on us.  Realists note that structures “shape and shove” but don’t determine foreign policies.  Kenneth Waltz memorably wrote in 1997 that states “are free to do any fool thing they care to, but are likely to be rewarded for behavior that is responsive to structural pressures and punished for behavior that is not.”

One of the things that’s really curious about today’s world (and another about which Walt has written) is the strange condition of unipolarity.  Given the size of the power disparity between the United States and, well, everybody else, there are few structural constraints acting on American policymakers.  So one major input, structure, that should play a powerful role in constraining statesmen’s options, isn’t really working.

Thus far the results have been pretty disappointing.  American policymakers have tended to expansionism, to recklessness, and to grand strategies based on trying to dominate the world.  A (hopefully) interesting theoretical question I’m kicking around is, Under unipolarity, what constraints are acting, given that structure really isn’t, and is there any reason to believe that any of these constraints will start limiting American strategic options any time soon?  If there are no binding constraints in sight, aren’t we very likely (destined?) to continue with the primacy strategy we’ve followed more or less since 1991?

Thus far, it seems like the domestic inputs that Walt and Cindy Williams point to have provided policymakers a completely blank slate to do anything they wish–except choose grand strategies based on restraint.  A lot of us yearn for a strategy of restraint, but it seems to me that it’s going to take some pretty serious tinkering with domestic politics to get us there, given the factors described above and the absence of meaningful structural constraints.  As it is, we’re dealing with fundamentally unchecked power.  Which both realists and libertarians ought to be wary of.