The North Korean leader also visited a traffic control centre in Beijing before departing for Pyongyang on Wednesday afternoon.
Following the historic summit between Donald Kim and Kim Jong-Un, the government of North Korea is expected to facilitate the return of the remains of approximately 200 USA soldiers who died during the Korean War. In return Trump ordered the suspension of military exercises with South Korea, a longstanding demand of the Pyongyang regime.
"Obviously, we are at the very front end of the process, the detailed negotiations have not begun", Mattis told reporters on Wednesday.
President Donald Trump said North Korea had returned on Wednesday the remains of 200 us troops missing from the Korean War, although there was no official confirmation of the move from military authorities.
"The North Korea-China summit is another step forward in denuclearization", Cheong Wa Dae spokesman Kim Eui-kyeom said.
Koryo Tours' Simon Cockerell said that given how institutionally anti-American the DPRK is, the removal of anti-U.S. propaganda "may be the start of a real softening of rhetoric".
"Next week, with John Bolton and our entire team, to go over the details and to get this stuff done".
"(North Korea and China) helping each other and cooperating transcends the traditional relationship between the two countries, two parties, and shows that it is developing into a special relationship with no precedent", Kim was quoted as saying by the North's Korean Central News Agency.
Japan's government started missile-specific evacuation drills last March in addition to usual natural disaster and other drills, and has since conducted them in more than 20 towns around the country, including Tokyo.
That engagement has not, so far, occurred.
South Korean President Moon Jae-in on Wednesday called on North Korea to move quickly on presenting a clear plan of actionable steps that it will take to dismantle the nuclear program.
Roger D'Aquin, a retired security manager from New Orleans who voted for libertarian candidate Gary Johnson in 2016, said that he thought Trump's tactics with Kim worked, but added, "I have no confidence that Kim wants to cooperate and wants to get rid of his nukes".
"The discontinuation of nuclear tests is an important process for global disarmament, and the DPRK will join the worldwide desire and efforts for a total halt of nuclear tests", Han Tae Song, the North Korean ambassador to the United Nations had said.
One of the officials who spoke to CNN suggested the White House could send an envoy to Pyongyang to collect the remains and escort them home, rather than receiving them at the border, which would be a remarkable media event if it occurred.
North Korea could start the process of handing over the remains of troops, including Americans, missing from the Korean War within the next few days, two US officials told Reuters on Tuesday.
US and South Korean officials expect to discuss the issue Friday, with consultations expected to continue next week when the USA defense secretary travels to Seoul.
Recovery and repatriation has been happening on and off for decades.
North Korea has indicated for some time that it holds the remains of as many as 200 American service members, though the identities of the personnel will have to be confirmed by military DNA testing.
Neither Trump nor Pompeo so much as mentioned "human rights" during their comments about North Korea over the past two days.