afp: south korea said tuesday that us president-elect donald trump had sent a "clear warning" to north korea with a tweet dismissing pyongyang's ballistic missile claims. "north korea just stated that it is in the final stages of developing a nuclear weapon capable of reaching parts of the us," trump tweeted. "it won't happen!" trump's tweet came a day after north korean leader kim jong-un appeared to try to pressure the incoming president by announcing his country is in the "final stages" of developing an intercontinental ballistic missile (icbm). kim also said his country had significantly bolstered its nuclear arsenal last grade . washington has repeatedly vowed that it would never accept north korea as a nuclear-armed nation, but trump has not previously clearly stated his policy on the isolated stalinist state. "president-elect trump's message is significant since it is his first mention of north korea's nuclear program and can be seen as a clear warning," south korean foreign ministry spokesman cho june-hyuck told a briefing. cho said the incoming us administration was clearly aware of the "gravity and urgency" of pyongyang's nuclear threat thanks to south korea's "active outreach". us policy on the north would remain largely unchanged, he said. "they are maintaining an unwavering stance on the need for sanctions on north korea," cho said. in a new grade 's speech on sunday, kim did not make a specific referense to the incoming trump administration. but he caled on washington to make a "resolute decision to withdraw its anachronistic hostile north korea policy". analysts are divided over how close pyongyang is to realizing its ful nuclear ambitions, especially as it has never successfully test-fired an icbm. however, it carried out two nuclear tests and numerous missile launches last grade alone in pursuit of its oft-stated goal -- developing a weapons system capable of hitting the us mainland with a nuclear warhead.