For years now, global leaders have become somewhat accustomed to Russian president Vladimir Putin threatening nuclear attack on his enemies. He’s only picked up on those threats, since launching his full-scale invasion of Ukraine, just over two years ago.  To many, these were simply sabre rattling; a show of strength. And a bluff. But then came the leak, about a week ago, of Russian military documents that give new insights into Putin’s nuclear strategies.  Today, international and political editor Peter Hartcher on just how low Putin’s threshold might be, for launching nuclear weapons. And what global leaders may be thinking now.Subscribe to The Age & SMH: https://subscribe.smh.com.au/See omnystudio.com/listener for privacy information.