Ross Douthat gets it:

As a general post-Cold War rule, Russia’s relative weakness on the global stage means that the United States doesn’t need to take a kid-gloves approach to the Kremlin when their interests and ours diverge. But at this specific moment, the U.S. is engaged in extremely costly, extremely important nation-building, counter-insurgency and counter-proliferation efforts involving countries that border on the Russian near abroad. And as long as the locus of the War on Terror (or the struggle against Islamist extremism, or whatever you want to call it) remains in Iran, Iraq, and Central Asia – as opposed to, say, the Andean highlands, or some other place where Russia’s influence and capacity for mischief are pretty negligible – it seems imprudent, to put it mildly, to simultaneously launch ourselves into a proxy war with one of the largest countries in the region. Diplomatically, we should of course be taking Georgia’s side right now; militarily, not so much.