Vladimir Putin and the FSB have not commented on Islamic State’s claim of responsibility for the concert hall attack but allege – without evidence – the gunmen had accomplices in Ukraine. Photograph: AFP via Getty Images The terror attack on a Moscow concert hall last Friday exposed deep flaws in the security apparatus that underpins Vladimir Putin’s regime, but the autocratic system built by Russia’s veteran leader will ensure that he evades responsibility for its failings. During 24 years in power, Putin has portrayed himself as Russia’s defender-in-chief against domestic and international enemies – initially pro-independence and Islamist groups based...