US President Donald Trump said on Monday his historic summit with North Korean leader Kim Jong Un in Singapore could “work out very nicely” as officials from both countries sought to narrow differences on how to end a nuclear stand-off on the Korean peninsula.

Kim, one of the world’s most reclusive leaders, made an evening tour of sites on Singapore’s waterfront, on the eve of the summit that is due to get underway on Tuesday morning at a nearby resort island.

While Trump was optimistic about prospects for the summit between the old foes, US Secretary of State Mike Pompeo injected a note of caution ahead of the first-ever meeting of sitting US and North Korean leaders, saying it remained to be seen whether Kim was sincere about his willingness to denuclearise.

Officials from the two sides held last-minute talks aimed at laying the groundwork for a meeting that was almost unthinkable just months ago when the two leaders were exchanging insults and threats that raised fears of war.

But after a flurry of diplomatic overtures eased tension in recent months, the two leaders are now headed for a history-making handshake that US officials hope could eventually lead to the dismantling of a North Korean nuclear programme that threatens the United States.

Offering a preview to reporters, Pompeo said it could provide “an unprecedented opportunity to change the trajectory of our relationship and bring peace and prosperity” to North Korea. However, he played down the possibility of a quick breakthrough and said the summit should set the framework for “the hard work that will follow”.