Actually we have no interest in entering this dispute. It's way too far from our borders and we simply don't possess enough resources to project our power that far south let alone our Pacific fleet is not very numerous in comparison to deployed forces of China and the US in the region. But what is more: we could not care less about those islands as long as it doesn't end up in a huge regional war with tactical nukes, which is de-facto hardly possible in 2-3 decades.
So for Russia it is very pointless to drag itself into a dispute that has no connection with its national interests. We have enough problems in our neighlouring regions and with islamists, havent't we?