Anyone who was expecting the "anti-war" presidential candidate Barack Obama to be anything like an anti-war president was simply not paying sufficient attention to how he campaigned. It wasn't just the daily vows to escalate in Afghanistan, or the repeated promises to act "unilaterally" if need be. It was, as then-Reason Associate Editor David Weigel reported in 2008, that "he has called for, or retroactively endorsed, interventions in Zimbabwe, Pakistan, and Sudan."

So we knew that President Obama would not be anti-war, but rather anti-dumb-war, however defined by his braintrust. And we further knew that said braintrust would largely be copacetic with the post-Munich, post-Bosnia worldview of Madeleine Albright, Samantha Power, and a generation of foreign policy minds flexible enough to oppose the war in Iraq almost at least half as vociferously as they endorsed war in Kosovo.

But what we didn't know was, where do they draw the all-important line of whether and when the United States should use deadly force? Until last night, that is.

"We knew that…if we waited one more day, Benghazi, a city nearly the size of Charlotte, could suffer a massacre that would have reverberated across the region and stained the conscience of the world," the president said last night. "It was not in our national interest to let that happen. I refused to let that happen….Some nations may be able to turn a blind eye to atrocities in other countries. The United States of America is different. And as president, I refused to wait for the images of slaughter and mass graves before taking action."

Do you remember when Democrats recoiled at the doctrine of preemptive war? Last night was the final reminder that, with the exception of some diehards like Rep. Dennis Kucinich (D-Ohio), Democrats when wielding power are only against Republican preemptive war. If anything, they are more promiscuous in choosing conflicts than their warmaking brethren on the other side of the aisle; just less likely to go all-in with ground troops. Does it satisfy the consciences of Bush-hating interventionists merely that Obama made more nice-sounding comments about subsuming America's lead role within a United Nations-blessed coalition? And have they thought through even for one moment the kind of bar-lowering precedent they're setting for the next Republican president to send ground troops into wherever the hell?

This latter question is not rhetorical, and the answer to it is occasion for despair. Here's what Deputy National Security Adviser Denis McDonough told the Associated Press in an article published yesterday: "[W]e don't get very hung up on this question of precedent because we don't make decisions about questions like intervention based on consistency or precedent. We base them on how we can best advance our interests in the region."

Set aside the administration's ever-elastic definition of "interests," and instead grok this: The Democratic foreign policy best and brightest have admittedly adopted as their causus belli for dropping bombs on a sovereign country the same test that former Supreme Court Justice Potter Stewart used for pornography: They know it when they see it. As for the rest of us taxpaying, war-weary plebes, we'll receive an "update" from the president now and then to let us know where his own eyes have taken him next.

So what's the danger of selectively and opportunistically preventing massacres? In Obama's relentless Third Way or Goldilocks-style interventionism—in which he's constantly taking some mythical middle road between the never-existing option of "turn[ing] away from the world" and a more plausible John McCain-style unrestrained war—there are always the dangers of an undefined mission, a fraying coalition, and a potential stalemate that exposes the faultline between a U.S.-led military action that falls short of beheading Libya's leader and an official U.S. policy that aims to accomplish precisely that task through some kind of non-military means.

But those are short-term concerns that may all turn out as well as can be expected. The medium-term issue is whether Washington has now irreversibly thumbed the scale on Arab Spring, making a complicated, sometimes thrilling and sometimes harrowing story of cross-border liberation into a conventional up-down question of America's will and blatant inconsistency on human rights. You could see that mission creep last night in Obama's own remarks, when he said things like, "I made it clear that Qaddafi had lost the confidence of his people and the legitimacy to lead, and I said that he needed to step down from power." And you could especially see it when he gave a stirring and inaccurate Bush-like boast that "wherever people long to be free, they will find a friend in the United States." (Tell it to the poor saps who live in Saudi Arabia and Bahrain, Mr. President.)

The Arab Spring, if the history of post-communist Europe is any guide (and it may not be!), will be successful in proportion to the ownership that the post-totalitarian countries have of their own revolutions and transitions. Injecting the overwhelming force of America into that process will, I think, delay, and not speed up, the eventual and hopefully inevitable Liberation Day.

And for those Democrats who are either cheering on or grimly supporting the president's actions, just remember this: Unless a Ron Paul-type miraculously emerges from the GOP field, the next Republican president now has an even lower bar than before when it comes to launching a preemptive war. There's a reason why the biggest fans of last night's speech were hawks like William Kristol: If you didn't like Iraq, you really won't like Iran. And when that day comes, please don't debase yourselves by crying crocodile tears over the Constitution, or pretending for even one second you are anti-war.

Matt Welch (matt.welch@reason.com) is Editor in Chief of Reason, author of McCain: The Myth of a Maverick; and co-author with Nick Gillespie of the forthcoming The Declaration of Independents: How Libertarian Politics Can Fix What's Wrong with America.