That decision has raised concerns about the risk of holding such a monumental meeting with barely anyone to bear witness. Now, he's posing for smiling selfies ahead of his meeting with President Donald Trump. "It starts between our two countries", so any discussion "would be premature as we wait for the outcome of the negotiations" in Singapore, Mattis added.
Trump spoke as numerous foreign policy analysts pointed out that Trump-Kim agreement cites only intentions to denuclearize, with no specifics about how to get that done.
The president reminded critics that since he first agreed to meet Kim Jong-un, North Korea stopped testing nuclear weapons, paused missile launches, and returned American hostages to the United States.
Predicting a tremendous success of the summit with the DPRK leader, Trump said that it was "an honor" to meet face-to-face with Kim and that he would have "a terrific relationship" with the DPRK leader.
Kim has offered to deal away his nuclear arsenal but doubts remain over whether he is truly willing to give up his nukes or is using the summit to weaken US-led sanctions against his country.
The PBS NewsHour's Nick Schifrin tells managing editor and anchor Judy Woodruff the latest from Singapore. "And you can be sure that President Trump will not stand for a bad deal", the secretary said.
North Korean leader Kim Jong-un meets with former National Basketball Association star Dennis Rodman in Pyongyang in September, 2013.
The talks involving other officials were scheduled to run until 11:30 a.m., followed by lunch. Central Intelligence Agency chief Mike Pompeo, now secretary of state, secretly met with Kim shortly afterward, setting in motion the sometimes tense negotiations that led to Monday's meeting at the very highest level.
Before that, the top story in North Korea was tremendously mundane by comparison: a full account of Mr Kim's trip to a seafood restaurant in Pyongyang. Carter is the first former USA president to visit North Korea.
After Trump's stern speech about North Korea's nuclear weapon program last November, Kim's government responded by calling the USA president an "old lunatic" - to which Trump responded by passively calling the North Korean leader "short and fat".
The expanded meeting came after the one-on-one session between Kim and Trump, which the US leader described as "very, very good". Kim emerged from the Tuesday morning talks saying their encounter was "a big prelude to peace", to which Trump agreed.
The eccentric former reality television star is one of the few westerners to have spent time with Kim during multiple visits to Pyongyang.
The U.S. seeks the complete, verifiable and irreversible dismantlement of the North's nuclear weapons program, whereas the North advocates a broader definition that also includes the removal of the U.S. nuclear umbrella over South Korea and Japan. But he also said the summit would be part of a "process".