Let's be clear about this. They don't claim to be debt free, only to have got rid of the legacy debts as of April 2013. I would imagine since then they have run up some new debts.
http://www.telegraph.co.uk/news/worldnews/europe/germany/10985678/Russia-should-be-stripped-of-World-Cup-after-MH17-attack-say-German-politicians.html
But I suppose four years is a very long time in world politics.
Russian press conference presenting their satellite and radar data.
http://player.rutv.ru/iframe/video/id/822433/acc_video_id/610598/isPlay/false/time_play/1/