573 people killed at an industrial complex , north of the zone . All South Koreans not cleared to cross the border into South Korea illegally . Follows vow to retaliate from N. Korea if its satellite launch is intercepted . North Korea said the military phone lines with the South , the last remaining communications channel , will remain closed until the 12-day military exercises end on March 20 , according to Yonhap . North Korea , who have started their annual joint military exercises .
573 people killed at an industrial complex , north of the zone . All South Koreans not cleared to cross the border into South Korea illegally . Follows vow to retaliate from N. Korea if its satellite launch is intercepted . North Korea , who have started their annual joint military exercises .