Donald Trump said he is on a "mission of peace" as he prepares to leave the G7 summit for Singapore to meet Kim Jong Un.
President Trump told reporters in Canada he would "know within a minute" whether Mr Kim is serious about giving up his nuclear weapons.
The US President added that he would not prolong talks if he sensed otherwise.
President Trump is set to board a plane from Quebec ahead of his highly-anticipated summit with the North Korean leader, leaving G7 leaders early and missing environmental talks.
Speaking to press before his flight, Mr Trump said Mr Kim "wants to do something great for his people".
He called the meeting a "one-time shot" for peace and denuclearisation, and said he thought the North Korean leader was "going to do something positive" for his people.
"I think it's going to work out well," he told reporters.
"All systems go"
Preparations are well under way in Singapore for the historic summit, after weeks of uncertainty over whether the planned meeting would go ahead.
It will take place at a hotel on the small tourist resort island of Sentosa, which is connected to the main city by a single bridge.
Singapore's Minister for Foreign Affairs Vivian Balakrishnan has returned home following a visit to Pyongyang in advance of the June 12th summit.
In comments quoted by The Straits Times, the diplomat added that it was “all systems go” for the summit.
Just wrapped up a fascinating first visit to Pyongyang at the invitation of DPRK FM Ri Yong Ho. I deeply appreciate the warm hospitality extended by the hosts to me and my delegation. I had open, friendly and... https://t.co/ijPG7M5LGg
— Vivian Balakrishnan (@VivianBala) June 9, 2018
Writing on Facebook after the visit, he said: "[It's] admirable that the [Democratic People's Republic of Korea] has overcome the challenges and obstacles that it has faced over the last decades to achieve this level of development. This could only have been possible through the sheer determination, self-reliance, strength of spirit, and resilience of the DPRK people.
"Imagine how much more the DPRK could achieve in times of peace, and with greater exchanges with the world. We look forward to the US-DPRK Summit on 12 June, and hope it will be another step towards achieving lasting peace in the Korean Peninsula and the world."
