SINGAPORE (AP) — President Donald Trump cast his Tuesday summit with North Korea’s Kim Jong Un as a “one-time shot” for the autocratic leader to ditch his nuclear weapons and enter the community of nations, saying he would know within moments if Kim is serious about the talks. Trump said Saturday he was embarking on a “mission of peace,” as he departed the Group of Seven meeting in Canada to fly to the summit site in Singapore. Saying he has a “clear objective in mind” to convince Kim to abandon his nuclear program in exchange for unspecified “protections” from the U.S., Trump acknowledged that the direction of the high-stakes meeting is unpredictable, adding it “will always be spur of the moment.” “It’s unknown territory in the truest sense, but I really feel confident,” he told reporters. “I feel that Kim Jong Un wants to do something great for his people and he has that opportunity and he won’t have that opportunity again.” “It’s a one-time shot and I think it’s going to work out very well,” he said. Raising expectations in advance of the meeting, Trump said the outcome will rely heavily on his own instincts. The U.S. president, who prides himself on his deal-making prowess, said he will know “within the first minute” of meeting Kim whether the North Korean leader is serious about the nuclear negotiations. “I think I’ll know pretty quickly whether or not, in my opinion, something positive will happen. And if I think it won’t happen, I’m not going to waste my time. I don’t want to waste his time,” Trump said. Trump has said he believes Kim would agree to denuclearization — and Secretary of State Mike Pompeo said Thursday he had received Kim’s personal assurances to that effect — but the two countries have offered differing visions of what that would entail. Despite Kim’s apparent eagerness for a summit with Trump, there are doubts that he would fully relinquish his nuclear arsenal, which he may see as his guarantee of survival. U.S. defense and intelligence officials have assessed the North to be on the threshold of having the capability to strike anywhere in the continental U.S. with a nuclear-tipped missile — a capacity that Trump and other U.S. officials have said they would not tolerate. Trump reiterated his promise Saturday that the U.S. “will watch over and we’ll protect” Kim and his government in return for him giving up the nuclear program. He also indicated that South Korea, China and Japan would be prepared to invest in the North to boost its besieged economy.