The US leader met with Shinzo Abe to talk about secretive state following rising tensions after the billionaire tycoon sent an aircraft carrier to the Korean peninsula in a show of force against the regime, which has refused to end its nuclear weapons programme.
Mr Trump insisted the “North Korea problem” would be “solved” after Pyongyang carried out repeated missile tests in the past year.
Speaking after meeting with Mr Abe, the leader said: “We’ll be discussing many things including of course North Korea, which is very much on our minds.
Donald Trump vowed to "solve" the "North Korea problem"
It will be solved at some point, it will be solved – you can bet on that
“We’ll be discussing terrorism but I think there will really be a particular focus on the North Korea problem – it’s a big problem it’s a world problem.
“And it will be solved at some point, it will be solved – you can bet on that.”
He then spoke of his close “friendship” with the Japanese leader and collaboration with the country.
Revealed: Kim Jong-un's nuclear cronies
Fri, May 26, 2017
After North Korea's recent series of ballistic missile test, dictator Kim Jong-un is often photographed with the same three men
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Kim Jong-un reacts during the long-range Hwasong-12 (Mars-12) strategic ballistic rocket test launch with Ri Pyong Chol (2nd L), Kim Jong Sik (C) and Jang Chang Ha (2nd R)
President Trump said: “It is a close partnership and collaboration and friendship. We’ve developed a great friendship and I look forward to being with you [Mr Abe] and spending some time with you.”
Meeting before the G7 summit, the pair dedicated much of their discussions to the issue.
"President Trump and Prime Minister Abe agreed their teams would cooperate to enhance sanctions on North Korea, including by identifying and sanctioning entities that support North Korea's ballistic missile and nuclear programs," the White House said in a statement to Reuters.
"They also agreed to further strengthen the alliance between the United States and Japan, to further each country's capability to deter and defend against threats from North Korea.”
The meeting comes as tensions grow, with North Korea accusing South Korea of a “reckless military provocation” after it fired warning shots at the border earlier this week.