The West risks causing one
It was and is not in Russian interest to start a Cold War. But the facts are pretty clear, the conflict in Caucasus was precipitated by the US who egged on the Georgians. The US completely miscalculated the Russian response, assuming it would bark but not bite (perhaps not an unreasonable assumption given the last 15 years, where Russia was too weak to respond with a credible use of force). But its been increasingly clear over the last two years or so, that the Kremlin has the economic/political/military coherence to respond with multiple instruments on its near abroad. Clearly, the US didnt take any of this seriously, and kept pushing eastwards.
Russia has now demonstrated that US/NATO post-1991 gains in Eastern Europe have reached their territorial limits in terms of new states that can now enter the western alliance, which is why they demonstrated their resolve using Georgia as an example for Russia’s red lines. (For instance, Ukraine could very well be the next battleground.)
But note what Russian President Dimitri Medvedev is saying—Russia does not wish a cold war, but is ready for it if the US wishes to raise the ante. At the same time, Old Europe will need to determine whether rising instability/conflict on their frontiers is more importan than Russian gas.
Bottom line: the Russians didnt start this Cold War, but will respond in kind if US doesn’t back down. Tangentially, US actions might be motivated in part by atleast the ongoing presidential campaign and the prevailing security establishment’s objectives to buttress the probability of a victory for Republican candidate John McCain. (The assumption is a reheating of the Cold War would diminish Democratic candidate Barack Obama’s chances in November).