Via TBA, this E. Luttwak piece argues that stalemate is the only outcome in Syria that serves U.S. interests. The case may seem logical. However, as the refugee population, already around one million, grows and places more strains on the host countries (Iraq, Lebanon, Jordan, Turkey), the political situation in the latter may become more tense and in some cases violent, as is already happening in Lebanon and Iraq. The U.S. has a humanitarian and possibly also strategic interest in seeing that the refugee problem does not become even worse than it is now, and that in turn makes an indefinite civil war an undesirable prospect (not to mention the suffering in Syria itself).
It's instructive to compare Luttwak's line with McCain's. For the latter, "our interests are our values." For the former, the 'realist' calculus is all that matters: both A and B are hostile to the U.S., therefore A and B should be encouraged to weaken each other by fighting each other indefinitely. Luttwak and McCain are both wrong. Values are one basic component of interests; the trick is to find a way to accommodate the entire package, so to speak, of interests, without claiming (a la McCain) that values exhaust interests because interests and values are identical, or (a la Luttwak) that values are essentially irrelevant to interests. Easier said than done? Yes.
Added later: And if there are no policy options that accommodate the whole 'package,' which there probably won't be (see previous decisions on Afghanistan, Libya, etc.), then that should be acknowledged, without pretending that the chosen option is better than it is.