In a wide-ranging interview with the BBC's Yalda Hakim, US National Security Adviser HR McMaster said that the United States has "to be prepared, if necessary, to compel the denuclearisation of North Korea", with or without their cooperation.

Donald Trump's top security aide also gave his views on Russia's meddling in the 2016 US election and the challenge of working around Trump's tweets.

Produced by Mat Morrison, John Landy, Pete Murtaugh, Ashley Semler and Paul Blake.