NEW : U.S. says it `` stands vigilantly by '' South Korea . NEW : North Korean leader Kim Jong Un is said to be in a state of shock after his country was hit with the heaviest artillery barrage on its capital since the 1950-53 war ended. U.S. will talk to North Korea , but Pyongyang has to talk giving up nukes , Kerry says . U.N. Secretary-General Ban Ki-moon told CNN 's Wolf Blitzer that the agency has no independent information to verify the DIA 's assessment . Ballistic missiles may be able to carry nukes , a U.S. defense intelligence assessment says .
NEW : U.S. says it `` stands vigilantly by '' South Korea . NEW : North Korean leader Kim Jong Un is said to be in a state of shock after his country was hit with the heaviest artillery barrage on its capital since the 1950-53 war ended. U.S. will talk to North Korea , but Pyongyang has to talk giving up nukes , Kerry says . Ballistic missiles may be able to carry nukes , a U.S. defense intelligence assessment says .