Russia seems to always (sometimes correctly) feel paranoid about Western powers (France, Britain). Russia also has a strong tradition of Slavic protectionism, probably stemming from it's mixed Byzantine heritage. Those factors make Serbia and it's Slavic inhabitants something of a Russian friend. Playing on the supposed 'Western Imperialism', Russia is the 'defender of Slavic heritage'. If anything, it's an attempt to look really powerful and benevolent.