. >> additional support has been provided by recognizance lyndh p. walter. bernard and irene schwartz. sue and et guard wachenheim iii. the sheryl and philip milstein family. and by contributions to your pbs station from viewers like you. thank you. >>> welcome to the program. i'm christiane amanpour in new york. there were hugs and hand shakes? pyongyang today as the south korean president moon jae-in arrived there for his third summit with the north korean leader kim jong-un. the two koreas are pushing ahead with their purity of peace on the peninsula, amid-mix the message from washington and facts on the ground that denuclearization talks are stalled and evidence that north korea is still developing its nuclear weapons program. across all fronts from trade to nato to the middle east, american diplomacy under president trump is unpredictable to say the least. his leader-to-leader personal negotiating style leaves his senior staff scrambling, and even undermining the president's promises. veteran diplomat william burn says the hollowing out of u.s. leadersh