North Korean leader Kim Jong Un arrived on Sunday in Singapore ahead of one of the most unusual and highly anticipated summits in recent world history — a sit-down with President Donald Trump meant to settle a standoff over Pyongyang’s nuclear bomb arsenal.

A few hours later, Trump also arrived in Singapore at the island city-state’s Paya Lebar Air Base, traveling from Canada, where he attended a meeting of the Group of Seven Nations (G7).

Trump’s high-risk meeting with Kim is scheduled for Tuesday.

The president hopes to win a legacy-making deal with the North to give up their nuclear weapons, though he has recently sought to manage expectations, saying that it may take more than one meeting.

This will be the first summit of its kind between a leader of North Korea and a sitting US president. The North has faced crippling diplomatic and economic sanctions as it has advanced development of its nuclear and ballistic missile programs.

Pope Francis on Sunday prayed that the summit succeeds in laying the groundwork for peace.

Francis expressed hope that Tuesday’s talks will “contribute to the development of a positive path that will assure a future of peace for the Korean Peninsula and the entire world”.

'Entire world watching'

A jet carrying Kim landed on Sunday afternoon amid huge security precautions on this city-state island. After shaking hands with the Singapore foreign minister, Kim sped through the city’s streets in a massive limousine, two large North Korean flags fluttering on the hood, surrounded by other black vehicles with tinted windows and bound for the luxurious and closely guarded St. Regis Hotel.

Kim smiled broadly on Sunday evening as he met with Singapore Prime Minister Lee Hsien Loong.

“The entire world is watching the historic summit between (North Korea) and the United States of America, and thanks to your sincere efforts [...] we were able to complete the preparations for the historic summit,” Kim told Lee through an interpreter.

The North Korean autocrat’s every move will be followed by 3,000 journalists who have converged on Singapore, and by gawkers around the world, up until he shakes hands with Trump on Tuesday. It’s a reflection of the intense global curiosity over Kim’s sudden turn to diplomacy in recent months after a slew of North Korean nuclear and missile tests last year raised serious fears of war.

The North, many experts believe, stands on the brink of being able to target the entire US mainland with its nuclear-armed missiles, and while there’s deep skepticism that Kim will quickly give up those hard-won nukes, there’s also some hope that diplomacy can replace the animosity between the US and the North.

Read: Trump says he will know in first minute if North Korea summit will succeed

Part of the interest in Tuesday’s summit is simply because Kim has had such limited appearances on the world stage. He has only publicly left his country three times since taking power after his father’s death in late 2011 — twice traveling to China and once across his shared border with the South to the southern part of the Demilitarized Zone in recent summits with the leaders of China and South Korea respectively.

But it is Kim’s pursuit of nuclear weapons that gives his meeting with Trump such high stakes. The meeting was initially meant to rid North Korea of its nuclear weapons, but the talks have been portrayed by Trump in recent days more as a get-to-know-you session. Trump has also raised the possibility of further summits and an agreement ending the Korean War by replacing the armistice signed in 1953 with a peace treaty. China and South Korea would have to sign off on any legal treaty.

Unclear outcome

It’s unclear what Trump and Kim might decide on Tuesday.

Pyongyang has said it is willing to deal away its entire nuclear arsenal if the United States provides it with a reliable security assurance and other benefits. But many say this is highly unlikely, given how hard it has been for Kim to build his program and that the weapons are seen as the major guarantee to holding onto his unchecked power.

Any nuclear deal will hinge on North Korea’s willingness to allow unfettered outside inspections of the country’s warheads and nuclear fuel, much of which is likely kept in a vast complex of underground facilities. Past nuclear deals have crumbled over North Korea’s reluctance to open its doors to outsiders.

Another possibility from the summit is a deal to end the Korean War, which North Korea has long demanded, presumably, in part, to get US troops off the Korean Peninsula and, eventually, pave the way for a North Korean-led unified Korea.

The fighting ended on July 27, 1953, but the war technically continues today because instead of a difficult-to-negotiate peace treaty, military officers for the US-led United Nations, North Korea and China signed an armistice that halted the fighting. The North may see a treaty — and its presumed safety assurances from Washington — as its best way of preserving the Kim family dynasty. The ensuing recognition as a “normal country” could then allow sanctions relief, and later international aid and investment.

Just meeting with Trump will also give Kim a recognition North Korea has long sought, setting him up as global player and equal to the US domestically and, internationally, as the leader of a “normal country” worthy of respect.