This week Boris Johnson outlined his security and defence strategy for the post-Brexit world.It included a plan to lift the number of nuclear warheads the UK is prepared to stockpile, a proposal to strengthen trade links with China and an ambition to make Britain a science and tech superpower.Adam Boulton is joined by Patricia Lewis, who leads in the International Security Programme at Chatham House; Sir Lawrence Freedman, the Emeritus Professor of War Studies at King’s College London and Sky's chief political correspondent Jon Craig to discuss what it means for Global Britain.