The UK, USA, and Australia announced a joint programme to build more nuclear submarines, and declared that China poses the biggest threat to the world economy of any country. It came following the inauguration of China’s President Xi Jinping’s precedent-setting third term in office, where he called for the country to modernise its military to make it a "Great Wall of Steel". On the Sky News Daily, Sally Lockwood is joined by our US correspondent Mark Stone, and Asia correspondent Helen-Ann Smith, to explore the rising tensions between the superpowers, and if the US-China relationship has any hope of cooling off soon. Producer: Rosie Gillott Interviews Producer: Alex Edden Editors: Philly Beaumont and Paul Stanworth