US President Donald Trump (L) shakes hands with North Korea's leader Kim Jong Un following a meeting at the Sofitel Legend Metropole hotel in Hanoi on February 27, 2019. (Photo by SAUL LOEB / AFP)
HANOI: US President Donald Trump urged North Korea's Kim Jong Un to go "all in" during their high-stakes nuclear negotiations but talks floundered amid differences over sanctions and the definition of "denuclearization", a senior State Department official said on Friday.