Call this the credibility conundrum. The imperative of maintaining America’s reputation for resolve has been implicit in the administration’s case, but those outside government who favor a strike, or something even bigger, have also stressed it. Yet the purpose for which Obama wants to protect his credibility is hard to divine, particularly because the benefits (for the United States or for suffering Syrians) are not self-evident and haven’t been clarified by the administration or those backing its position.

This, along with the public’s inattentiveness to the war in Syria, explains why so many Americans (close to 80 percent, based on polling data) wanted Congress to weigh in even before Obama decided pause and seek its consent. As NPR’s Alan Greenblatt has observed, what’s going on here is not a sudden surge in public confidence in the Congress but an expression of Americans’ reticence and confusion. Who can blame them?

As for the folks pushing for a much grander version of intervention—bigger military strikes than Obama plans and the large-scale, sustained supply of arms and training to the Syrian opposition’s “moderates”—you have to hand it to them. They do have a strategy: toppling Assad, isolating the Islamist hardliners, and helping the Syrian groups that they deemed best suited to run Syria. QED.

This scheme is seriously flawed on several counts. Changing the balance of forces on the battlefield so that Syria’s weakest combatants become its strongest will require a lot of arms, training, and time. Even then the odds are long. The interventionists’ plan could ultimately (even quickly) necessitate the creation of a no-fly zone over Syria, the protection of “safe areas” established for training and for supply channels, and the deployment of American trainers. This would implicate the United States in the war as never before and increase its role in ways that haven’t been thought through by the interventionists, never mind that some are influential regarded strategists. Then there’s the blithe assumption that in Syria’s chaotic conditions, where weapons are free-flowing and bought and sold in all manner of ways, it’s possible to ensure that only those you favor get your guns and that those you oppose will not.

What’s also missing from this plan to prevail at the front (the battlefield) is a consideration of the significance of the rear (America’s polity and society), which is essential for its success. The American public does not want to wade deeper into Syria just as the United States has emerged from Iraq and is exiting Afghanistan. Only 50 percent support even a calibrated attack on Syria that’s limited to airpower and missiles. But once you start down the interventionists’ road, there’s no easy way back, especially if the favored groups turn out to require more support than was surmised. That’s why a strategy that focuses on the front alone is foolish.

Syria’s war is not simply a contest that pits Sunni insurgents against Assad, his Alawite base, and those Christians, secular Sunnis, and other communities that have stuck with him, fearing that the triumph of the most doctrinaire Sunni groups would leave them vulnerable. The Sunnis battling Assad are themselves divided. The fighting among them, though muted by the overriding imperative of ousting Assad, is part of the Syrian saga and will become an even more prominent part should the objective of the opposition groups shift from wrecking the House of Assad to ruling the new Syria.

This means that the other contestants will hardly sit still once the United States starts arming its favorite Sunni groups on a large scale; they have their patrons and their own ways of procuring weapons and will double their efforts in preparation for the endgame. They haven’t bled and died in large numbers in order to hand the house keys to others. So one (presumably unintended) consequence of the interventionists’ gambit will be continued war and Syria’s transmutation into a version of what Lebanon was during the worst years of its civil war—a process already discernible. Another will be the exacerbation of Sunni-Shia strife in Lebanon, Syria and parts beyond, as the war becomes further internationalized.

The bloodiest wars since 1945 have, in the main, occurred not among states but within them. The particulars are of course very different, but the conflicts in, for example, Rwanda, the Congo, and Darfur are comparable to Syria in this one respect. There is a natural inclination to “do something” in the face of massive bloodletting. But in Syria that “something,” if it is to be substantial rather than symbolic, will require a campaign involving not just airpower but also ground troops—unless the interventionists are prepared to say “thus far and no further” for a cause they insist is so morally and strategically important.

Moreover, if Assad is swept away, there will have to be a follow-on phase of peace brokering and institution building given the divisions among Syria’s opposition forces. The countries that intervene will have to play a big role—sooner than expected and with less and less approval from Syrians as time goes by. Then there’s the business of rebuilding an economically shattered Syria.

This is what a serious project for intervention would look like. No Western government—and very few Western citizens—want to be part of it. The idea that the task won’t be so complicated or take very long is fanciful. We’ve heard these happy reassurances before.

Rajan Menon is the Anne and Bernard Spitzer Professor of Political Science at the City College of New York/City University of New York, a nonresident senior fellow at the Atlantic Council and the author, most recently, of The End of Alliances (Oxford University Press, 2007).