Russian President Vladimir Putin acknowledged that the attack on the concert hall in suburban Moscow was carried out by Islamic militants on Monday but suggested that it benefitted Ukraine and that Kyiv may have played a role. He said 11 people had been detained, including the four suspected gunmen, who he said had made their way to the Bryansk region and tried to slip into Ukraine. In the deadliest attack inside Russia for two decades, four men burst into the Crocus City Hall on Friday night, spraying bullets during a concert by the Soviet-era rock group Piknik. The Russian President...