Taiwan have become the first country to advise its people to stay away from Korea.
American intelligence officers in South Korea say they have seen enough evidence to expect a missile test "any time now".
Daybreak's Richard Gaisford reports from Seoul.
Through her tears, a North Korean woman told me how she had to escape: risk death while running across the border or die of starvation.
Memories of the Korean war are never far away in South Korea, where residents have grown used to living with the constant threat of war.
North Korea said it will withdraw workers from the Kaesong factory park run jointly with South Korea and suspend all operations there.