2. The U.S. Has No Serious Enemies.
A second factor that permits the United States to keep waging these optional wars is the fact that the end of the Cold War left the United States in a remarkably safe position. There are no great powers in the Western hemisphere; we have no "peer competitors" anywhere (though China may become one sooner if we keep squandering our power foolishly); and there is no country anywhere that could entertain the idea of attacking America without inviting its own destruction. We do face a vexing terrorism problem, but that danger is probably exaggerated, is partly a reaction to our tendency to meddle in other countries, and is best managed in other ways. It's really quite ironic: Because the American homeland is safe from serious external dangers (which is a good thing), Americans have the luxury of going abroad "in search of monsters to destroy" (which is not). If Americans were really worried about having to defend our own soil against a powerful adversary, we wouldn't be wasting time and money on feel-good projects like the Libyan crusade. But our exceptionally favorable geopolitical position allows us to do these things, even when they don't make a lot of strategic sense.
3. The All-Volunteer Force.
A third enabling factor behind our addiction to adventurism is the all-volunteer force. By limiting military service only to those individuals who volunteer to do it, public opposition to wars of choice is more easily contained. Could Bush or Obama have kept the Iraq and Afghanistan wars going if most young Americans had to register for a draft, and if the sons and daughters of Wall Street bankers were being sent in harm's way because they got an unlucky number in the draft? I very much doubt it.
By the way, I am not saying that the AVF is a bad idea that should be chucked, as there are a number of good arguments in its favor. Nonetheless, the AVF is one of those features of the contemporary U.S. national security order that makes the frequent resort to force politically feasible.
4. It's the Establishment, Stupid.
A fourth reason we keep meddling all over the world is the fact that the foreign-policy establishment is hard-wired in favor of "doing something." Foreign-policy thinking in Washington is dominated either by neoconservatives (who openly proclaim the need to export "liberty" and never met a war they didn't like) or by "liberal interventionists" who are just as enthusiastic about using military power to solve problems, provided they can engineer some sort of multilateral cover for it. Liberal interventionists sometimes concede that the United States can't solve every problem (at least not at the same time), but they still think that the United States is the "indispensable" nation and they want us to solve as many of the world's problems as we possibly can.
These worldviews are developed, promulgated, and defended by a network of think tanks, committees, public policy schools, and government agencies that don't always agree on what should be done (or which problems deserve most priority) but that are all committed to using U.S. power a lot. In short, our foreign policy is shaped by a bipartisan class of foreign policy do-gooders who spend years out of power maneuvering to get in, and spend their time in office trying to advance whatever their own pet project(s) might be. Having scratched and clawed to get themselves on the inside, the people who run our foreign policy are not likely to counsel restraint, or to suggest that the United States and the rest of the world might be better off if Washington did a bit less. After all, what's the point of being a big shot in Washington if you can't use all that power to try to mold the world to your liking?
Compared with most Americans, this is a wealthy, privileged, highly educated group of people and most of them are personally insulated from the consequences of the policies they advocate (i.e., with a few exceptions, their kids don't serve in the military -- see
No. 3). Advocates of intervention are unlikely to suffer severe financial reverses or face long-term career penalties if some foreign war goes badly; they'll just go back to the same think-tank sinecures when their term of service is over.
By the way, lurking underneath the Establishment consensus on foreign-policy activism is the most successful Jedi mind trick that the American right ever pulled. Since the mid-1960s, American conservatism has waged a relentless and successful campaign to convince U.S. voters that it is wasteful, foolish, and stupid to pay taxes to support domestic programs here at home, but it is our patriotic duty to pay taxes to support a military establishment that costs more than all other militaries put together and that is used not to defend American soil but to fight wars mostly on behalf of other people. In other words, Americans became convinced that it was wrong to spend tax revenues on things that would help their fellow citizens (like good schools, health care, roads, and bridges, high-speed rail, etc.), but it was perfectly OK to tax Americans (though of course not the richest Americans) and spend the money on foreign wars. And we bought it. Moreover, there doesn't seem to be an effective mechanism to force the president to actually face and confront the trade-offs between the money he spends on optional wars and the domestic programs that eventually have to be cut back home. Which brings me to
No. 5.
5. Congress Has Checked Out.
The authority to declare war is given to Congress, not the president, but that authority has been steadily usurped ever since World War II. Although the Constitution could not be clearer on this point, modern presidents clearly feel no constraints about ordering U.S. forces to attack other countries, or even to fully inform Congress as to what we might be doing in secret. In practice, therefore, the vaunted system of "checks and balances" supposedly enshrined in our Constitution simply doesn't operate anymore, which means that the use of America's military power has been left solely to the presidents and a handful of ambitious advisors (see No. 4 above). This is not to say that public opinion doesn't figure into their calculations (i.e., they've got pollsters and political advisors too), but it is hardly a binding constraint.
I've no doubt that one could add more items to this list (e.g., the passive press, the military-industrial complex, etc.), but the items already noted go a long way to explaining why the supposedly peace-loving United States keeps finding itself in all these small but draining wars.
Back in the 2008 campaign, Barack Obama said that his favorite movie was The Godfather. And if I recall correctly, he said his second favorite movie was The Godfather, Part II. But his presidency is starting to play out like Part III of that famed trilogy, where Michael Corleone rails against the fates that have foiled his attempt to make the Corleone family legit.
I can just hear Obama saying it: "Just when I thought I was out … they pull me back in." Precisely.
Is America Addicted to War? - By Stephen M. Walt | Foreign Policy