Jens Stoltenberg - Secretary General of NATO

Stephen Sackur is at Nato headquarters in Brussels to speak to Jens Stoltenberg, the organisation's secretary general. In some ways it's just like old times - Moscow is once again seen to pose a threat to Europe's eastern flank, and Nato leaders promise a robust, collective response. But a generation on from the Cold War - are they serious? The western world's military alliance has a proud history, but does it have a future?