The Russians believe that a declaration of independence is a bad thing, but they have ruled out sanctions against Kosovo.
This is a very positive development. One of the political imperatives in Russia is that it sees itself as a “Protector of the Slavs”, particularly those who subscribe to Orthodox Christianity, such as the Serbs.
They are behaving moderately because they recognize reality, and because, despite what the “very sensible people” in Washington say, Russia is not looking at reestablishing the USSR or the Warsaw Pact.
Their hostility toward the current path in US policy is because they feel that US policy is hostile towards them.