Pope Francis asked Russian President Vladimir Putin to end the “spiral of violence and death” the war in Ukraine is causing, his most urgent appeal yet in the seven-month-old conflict. The head of the Catholic Church’s message comes after Putin recently mobilized hundreds of thousands of reservists, illegally annexed parts of Ukraine and warned he wouldn’t hesitate to use nuclear weapons. Francis, speaking to the faithful in St Peter’s Square on Sunday, said his words were “addressed first and foremost” to the Kremlin leader. “What is to happen next? How much blood must still flow for us to re…