Pyongyang has stopped South Korean workers getting to Kaesong – a joint industrial zone they share, located in the North but employing several hundred workers from the South.
The move comes after North Korea threatened to attack South Korean and US targets and announced plans to re-opened its main nuclear complex.
The US Secretary of State John Kerry said: “We have heard an extraordinary amount of unacceptable rhetoric from the North Korean government in the last days, so let me be perfectly clear today. The United States will defend and protect ourselves and our treaty ally the Republic of Korea.”
North Korean leader Kim Jong-Un’s war rhetoric has been escalating. In a speech on April 1, he promoted nuclear strength as a way to bring prosperity to the nation.