The Kremlin said on Monday that no country was immune to terrorism when asked if there had been a major failure by security services in preventing Friday's deadly attack on a concert hall, the worst attack inside Russia for two decades. President Vladimir Putin said in an address to the nation on Saturday that all those responsible would be punished. Kremlin spokesman Dmitry Peskov said on Monday it was inappropriate to comment on a claim of responsibility for the attack by Islamic State while the investigation was live.