(3rd LD) N.K. leader vows to advance ties with China during surprise Dandong visit
(ATTN: ADDS more details about Kim's visit on Rodong Sinmun in paras 12-13)SEOUL, Oct. 25 (Yonhap) -- North Korean leader Kim Jong-un has visited China and vowed to promote the two countries' longstanding relationship forged in blood, state m
