How does North Korea raise foreign currency, and are the toughest economic sanctions in the world actually having any effect?

Ed Butler looks at one of the country's major sources of income - migrant workers. According to Artyom Lukin, professor of international relations at Russia's Far Eastern Federal University, the workers who used to frequent his hometown of Vladivostok have been shooed away by the Russian authorities.

But analyst Lee Sang Hyun of South Korea's Sejong Institute is sceptical that the Chinese are clamping down heavily on Pyongyang, while Ian Bremmer of US think tank the Eurasia Group says the American government has little to show for the pressure it has been applying.

(Picture: North Korean leader Kim Jong-Un; Credit: Mikhail Svetlov/Getty Images)