North Korean leader Kim Jong Un began a train journey to Vietnam on Saturday for a summit with President Donald Trump, Russia’s TASS news agency reported, citing an unidentified diplomatic official. Kim is due to meet Trump this week in Hanoi for their second summit after a meeting in June in Singapore, where they agreed to work toward the “complete denuclearization of the Korean Peninsula.” Progress has sputtered since then, with critics saying the statement failed to spell out how to achieve its key goals. Trump will meet with Kim one-on-one in Hanoi for a meal and have lengthier negotiations over North Korea’s nuclear ambitions, where they will be joined by aides, U.S.