NEW : North Korea blocks South Korean workers from jointly run industrial complex . The North Korea 's is `` fully prepared '' to defend itself , Ban Ki-moon says . Kaesong Industrial Complex Secretary-General Kerry `` deeply troubled '' about North Korea statements . The North says it is adapting and restarting facilities at its main nuclear complex .
NEW : North Korea blocks South Korean workers from jointly run industrial complex . The U.S. is `` fully prepared '' to defend itself , Kerry says . U.N. Secretary-General Ban Ki-moon `` deeply troubled '' about North Korea 's statements . The North says it is adapting and restarting facilities at its main nuclear complex .