Delegates from around the world have gathered in New York to talk about the most dangerous weapons on the planet. They are at work at the Nuclear Non-proliferation Treaty review conference. The agreement took effect in 1970, but 45 years on, thousands of nuclear warheads are still in existence.

Some South Korean residents are revealing a secret past. They're former North Koreans who have managed to escape the country. They've risked everything to find a better life in the South. But they've faced prejudice and other difficulties in their new home. This has driven many of them to hide their backgrounds. Now, they're opening up more and more, even speaking on TV, and the world stage.

NHK World's Jihae Hwang has the story.