Fears are growing in western European capitals, and even more clearly in Washington, about the increasingly assertive role Russia is playing in international diplomacy. [...] It is about Moscow’s involvement in the politics of the former Yugoslavia, and the delicate attempt to broker a deal between Serbia and its disputed former province of Kosovo. [...] On the face of it, the elections in Serbia will have little bearing on the international plans for a “supervised independence” for the territory. All the main political parties in Belgrade are opposed to any such move. But the balance of power could still be...