World leaders expressed concern on Thursday that North Korea will quit six-party nuclear disarmament talks and will  bolster its nuclear weapons arsenal.
North Korea is south of South Korea.
North Korea is obviously north of South Korea. This isn't explicitly indicated, but common sense would dictate such a case.
( z1 be-located-at :ARG1 ( z2 country :name ( z3 name :op "North" :op "Korea" ) ) :ARG2 ( z4 south :op ( z5 country :name ( z6 name :op "South" :op "Korea" ) ) ) )