Treasury Secretary Steve Mnuchin said on NBC'S "Meet the Press" that the USA would keep imposing heavy economic sanctions on North Korea ahead of the summit. Kono said a verbal promise of denuclearization is not enough and that he and Suh agreed that the two sides, along with the US, will keep pressuring North Korea until it fulfills the promise with concrete actions.
Cheng also said that while Beijing's role in the leaders' summits may be limited, "it's hard for North Korea to ignore China as China remains its neighbour and a country with veto power at the United Nations Security Council".
'I feel they're approaching this matter with caution and they need time to organise their stance'. He says that it's in the "very early stages".
"We are very grateful to China for its consistent position", he said.
Mr Trump agreed to meet Mr Kim by the end of May and the two Koreas will hold a summit by the end of next month.
North Korea has yet to issue any official response to Kim Jong-Un's agreement to hold a summit with South Korea in late April and a rare meeting with Trump by May.
He also called for continued cooperation among Japan, South Korea and the USA with regard to the nuclear and kidnapping issues going forward.
The two North Korean athletes, both of them skiers, competed in their first event Sunday, finishing last, and will join another event Wednesday. For that to happen, he said, "the United States will have to cease all joint South Korea-US military exercises, completely eliminate the global community's sanctions on North Korea, and to accept establishing diplomatic ties between the US and North Korea".
Tillerson spoke Monday at a news conference in Nigeria. The summit, which Trump said would take place by May, would be the first between a sitting USA president and a North Korean leader.
During the meeting with the ambassadors, McMaster pointed to three United Nations sanctions resolutions adopted by the council as key in the campaign to bring North Korea to the negotiating table, according to a council diplomat.
The South Korean officials who met Kim travelled to Washington last week to relay his message and visited China on Monday to brief President Xi Jinping, who urged patience.
Suh is scheduled to meet Prime Minister Shinzo Abe on Tuesday.
Xi told Chung the peninsula was "facing an important opportunity of mitigation and dialogue", according to state broadcaster CCTV.
Signing a peace treaty would require addressing issues regarding the US military's presence in South Korea and its transfer of wartime operational control to South Korea and United Nations forces there, Koh said.
The Republican president agreed on Thursday to accept an invitation from the North Korean leader to meet by May after months of escalating tensions over Pyongyang's advancing nuclear and missile programmes.
It has also proposed a "suspension-for-suspension" plan in which the United States, South Korea and Japan freeze military drills in return for North Korea halting its nuclear and missile tests. That means the Japanese and the South Koreans.