The organisation committee of the World Cup have called for calm. These types of incidents amongst ultras haven't happed in Russia for years, they assure. Furthermore, the security measures surrounding the matches in Russia will be strict and there simply will not be room for any violent confrontations during the World Cup.
Russia doesn't want fighting and, according to 'Marca', the Russian government has ordered an investigation following the incidents in Bilbao provoked by Spartak Moscow fans.
After the Bilbao match, during which a police officer was killed, Russian ultras are on everybody's radar. UEFA could dish out serious sanctions to any club or fan involved in these types of situation.
There is no serious debate about what could happen during the World Cup. It's an event that nobody wants to miss, but there is a sense of fear among foreign fans.