Islamists from the North Caucasus have claimed responsibility for the deadly bombing of the Russian passenger train on Friday. According to a statement posted today on a website linked to Chechen rebels, the operation was prepared and executed along with other acts of sabotage, planned from the start of this year. It said the operation was successfully carried out against a set of strategically important sites in Russia, on the orders of Caucasus Emir Dokku Umarov. Umarov is the self-proclaimed leader of the Caucasus Emirate, which has sought to unite various Islamist groups in Russia's North Caucasus and establish Islamic Sharia rule in the region. The bombing killed 27 people and injured around 100 more passengers on the Nevsky Express, an upscale passenger train running from Moscow to Saint Petersburg.