North Korea's nuclear threats North Korea issued new threats against South Korea,

 
South Korean soldiers walk through smoke as they take part in an anti-terror and security drill at the Integrated Government Complex in Sejong, south of Seoul, April 17, 2013. North Korea issued new threats against South Korea on Tuesday, vowing "sledge-hammer blows" of retaliation if South Korea did not apologize for anti-North Korean protests the previous day when the North was celebrating the birth of its founding leader. REUTERS/Kim Hong-Ji (SOUTH KOREA - Tags: POLITICS MILITARY TPX IMAGES OF THE DAY)
 

A South Korean army soldier uses his radio at barricaded Unification Bridge near the border village of Panmunjom, that has separated the two Koreas since the Korean War, in Paju, north of Seoul, South Korea, Wednesday, April 10, 2013. A few hundred South Korean managers, some wandering among quiet assembly lines, were all that remained Tuesday at the massive industrial park run by the rival Koreas after North Korea pulled its more than 50,000 workers from the complex. Other managers stuffed their cars full of finished goods before heading south across the Demilitarized Zone that divides the nations. (AP Photo/Lee Jin-man)