http://www.theguardian.com/football/blog/2014/aug/19/2018-world-cup-russian-cup-crimean-teams?CMP=twt_gu
All to do with Crimea.
Crimean teams have been playing in the Russian Cup and teams from one country are not allowed to play in another's cup competition (apart from Cardiff, Swansea, Newport, Berwick Rangers etc obvs) and UEFA is yet to sanction the Crimean club's departure from the Ukrainian FA.