Shortly before a sold-out rock concert began, four gunmen opened fire on concertgoers with AK-type automatic weapons, as well as setting fires with incendiaries. Russian security forces were slow to respond to the attack, which at this time has claimed 139 dead, with more perhaps coming, since many of the nearly two hundred injured had life-threatening wounds.

How this happened in Russia, which is publicly vigilant about terrorism, with a particularly strong security presence in the Moscow region, is an embarrassing question for President Vladimir Putin. Not least because the almost quarter-century of Putin’s increasingly authoritarian rule in the Kremlin has featured Islamist terrorist atrocities – several of them murky in origin – as major turning points in his tenure. Now there’s been another one.