In the week of the new President's inauguration, Panorama reports on Russia's role in Donald Trump's election victory and asks what's behind the relationship between Vladimir Putin and Trump. Reporter John Sweeney - who has met and challenged both men - travels to Moscow and the United States to find out how sure we can be that Russian cyber-warriors influenced the US election and if there's any truth to claims that Russian intelligence has compromising material about the President elect. And from Lithuania and the battlefields of Ukraine, he investigates what this will mean for security in Europe and the rest of the world.