President Trump and Kim Jong-un prematurely concluded their summit in Vietnam on Thursday after reaching an impasse related to the lifting of existing international sanctions against North Korea.“Sometimes you have to walk,” Trump said during a press conference in Hanoi Thursday afternoon.Trump went on to explain that negotiations collapsed after Kim demanded that all international sanctions be lifted immediately in exchange for the closure of one major North Korean nuclear facility, but not an end to the nuclear program in its entirety.“It was about the sanctions,” Trump explained. “Basically they wanted the sanctions lifted in their entirety, but we couldn’t do that.”Negotiations have remained stalled since the last time the two leaders met in Singapore in June 2018 for a summit that produced a communique rife with vague commitments, but lacking in timelines and specific, verifiable action items. The U.S. continues to demand the complete shutdown of North Korea's nuclear faciliti...