A 20-year-old exchange student from Korea died after lying down in a 6ft-deep sandpit on a Californian beach when it collapsed on him.

The US Ambassador to South Korea today urged South Koreans to set aside their culture of collective guilt and not assume responsibility over the murder of 32 students and faculty members at Virginia Tech University.

North Korea has said it is preparing “strong measures for self-defence” after the US wrapped up a massive Pacific military exercise.