Given the timing of Russian President Dmitry Medvedev's visit to the Kuril Islands, it's hard to see it as anything other than an intentional effort to destabilize Japan, and particularly Prime Minister Naoto Kan. Coming in the aftermath of Tokyo's standoff with Beijing over the Senkaku Islands, it reinforces the perception of a weak Japan unable to make its territorial claims respected. The fact that this was a peripheral and largely frozen dispute that had until now not seriously affected improving bilateral relations adds to that impression.
The move also comes in the aftermath of Russia's refusal to support South Korean claims of North Korea's responsibility for the sinking of the Cheonan. I mentioned in a previous post on EU-Russian relations that Russian and Wetsern interests have begun to converge, now that NATO expansion and missile defense have been shelved or rolled back.
That might not be the case in Asia. Russia must still carefully position itself with regard to China's rise. But with regard to the zero-sum aspects of the strategic hedging taking place in Asia, Russia has less of an interest in seeing Japan and South Korea emerge as credible counterbalances to China's regional dominance (as opposed to India, for example). Although China represents a rival and potential threat in a number of areas for Russia, it also represents a customer in terms of oil and gas. And Moscow knows it will never have the same bonds as those shared by Tokyo and Seoul with Washington.