Donald Trump has said he would like to meet North Korean leader Kim Jong Un during his upcoming trip to Asia.

"I would. If you want to put out the word, I'm open to it," the US president told reporters onboard Air Force One as he departed for the region, adding that he "had a great relationship" with Kim.

Trump made history during his first term, becoming the first sitting US president to set foot into North Korea when they last shook hands in 2019.

His trip to Malaysia and Japan will see him meet a number of world leaders including China's Xi Jinping, amid trade negotiations sparked by Trump's imposition of sweeping tariffs earlier this year.

Trump has taken an atypical approach to North Korea - a secretive communist totalitarian state largely isolated on the world stage - and its attempts at creating nuclear weapons, initially taunting Kim as a "little rocket man".