U.S. President Donald Trump intends to meet one-on-one briefly with North Korean leader Kim Jong Un at the beginning of their June 12 summit — a moment the president has said will be a critical gauge of whether a deal is likely, according to a U.S. official familiar with their plans.

Trump said Saturday he thinks he'll know "within the first minute" if Kim is serious about giving up his nuclear arsenal and whether "something positive will happen." The current plan is for Trump and Kim to be alone for that first minute, although likely with translators in the room.

Trump and Kim will be joined later by their closest aides, including U.S. Secretary of State Mike Pompeo and national security adviser John Bolton, the official said. White House officials were told that Kim's sister, Kim Yo Jong — who represented North Korea in a diplomatic overture at the Winter Olympics — will also be present in Singapore.