The leaders of the United States and North Korea arrived have in Singapore ahead of a historic summit that could pave the way for wider negotiations to denuclearize the Korean peninsula, potentially laying aside historic bitterness and enmity between Washington and Pyongyang that has persisted for nearly seven decades since the 1950-53 Korean War.

US President Donald Trump and North Korean leader Kim Jong-un are expected to meet on June 12 at the Capella Hotel on the resort island of Sentosa. It will be the first time a sitting American president has met with a North Korean leader, a stunning turnaround from the saber-rattling and threats of destruction exchanged by the two sides only months ago.

The two leaders and their delegations are staying in luxury hotels in downtown Singapore, Trump at the Shangri-La Hotel and Kim at the St. Regis. Singapore, a wealthy Asian city-state, one of the few countries with ties to both the US and North Korea, is regarded as capable of ensuring the two leaders security while providing a neutral meeting ground.

Kim arrived at Singapore’s Changi Airport on Sunday, marking the start of the longest overseas trip taken by a recent North Korean leader. His aircraft, a Boeing 747 provided by Air China, appeared to maximize the amount of time it spent in Chinese airspace, taking an inland route over four Chinese provinces, according to flight trackers.

There were no civilian planes anywhere near Kim’s flight and a source from the South Korean air force cited by the South China Morning Post said China had controlled all air movements to provide Kim with maximum security. His motorcade of Mercedes-Benz sedans, police cars and a mobile hospital left the airport’s VIP complex around 3pm local time.

Kim traveling with sister, top aides

Traveling with the North Korean leader was his sister Kim Yo-jong, who is known to be his closest aide, accompanying him on both his visits to China last month, as well Minister of Foreign Affairs Ri Yong-ho and vice-chairman of the Central Committee Kim Yong-chol, who met with Trump in rare Oval Office discussions on June 1.

Police temporarily blocked traffic on entire roads and motorways, allowing for unimpeded passage for Kim’s Mercedes-Benz, a security protocol that Singapore’s own leaders forgo. North Korean guards were seen briefly jogging alongside Kim’s vehicle, while dozens more joined Singapore’s police to set up security checkpoints.

Speaking to reporters at the media center at the F1 Pit Building, which is expected to host some 2,500 journalists – the largest media contingent Singapore has ever seen, the country’s Law and Home Affairs Minister K Shanmugam said both the US and North Korean delegations had “very high requirements” that necessitated constant communications.

Kim met Singapore Prime Minister Lee Hsien Loong at the Istana, the working office of the premier, shortly after his arrival, passing excited crowds lining the streets. A beaming Kim posed for photographs with Lee and thanked him for hosting the summit, remarking that the “entire world is focusing on the historic summit between the DPRK and the US.”

Lee told reporters hours earlier that the historic meeting would cost Singapore about $20 million Singapore dollars (US$15 million), more than half of which would go on security, which he cast as his country’s “contribution to an international endeavor which is in our profound interest.”

Trump arrived shortly after, landing at Singapore’s Paya Lebar Air Base, an airfield used by past American leaders during visits to the city-state. Accompanying him were Secretary of State Mike Pompeo, National Security Adviser John Bolton, White House Chief of Staff John Kelly, White House Press Secretary Sarah Sanders and others.

The US President and his delegation were received by Prime Minister Lee at the Istana for a working lunch on Monday during which he thanked the premier for his “hospitality and professionalism” and expressed a commitment to continue engaging the region.

Trump tweeted ahead of the meeting saying it was “great to be in Singapore, excitement is in the air.” US Secretary of State Mike Pompeo, however, offered a more policy-oriented tweet, saying the US remained “committed to the complete, verifiable, irreversible denuclearization of the Korean peninsula”.

11th-hour talks by both sides

North Korean state media reports claimed the two adversarial countries’ leaders would discuss a “permanent and durable peace-keeping mechanism” on the Korean peninsula, denuclearization of the peninsula and other issues of mutual concern. US and North Korean officials also met at The Ritz-Carlton hotel on Monday, one day ahead of the summit.

The working-level 11th-hour talks were reportedly led by US ambassador to the Philippines Sung Kim, the State Department’s top Korean expert, and North Korean Vice-Foreign Minister Choe Son Hui. Both parties spent over two hours at the venue as a crowd of foreign and local journalists waited at the entrance during their discussions.

Reports on Monday described quiet at the St Regis hotel, where the North Korean delegation is staying. Meanwhile, South Korea’s President Moon Jae-in was “highly unlikely” to travel to Singapore to join the Trump-Kim summit, his office said. Many had speculated that the leader would attend a separate trilateral summit following the talks on Tuesday.

Seoul dispatched Nam Gwan Pyo, a deputy director of the Moon Administration’s National Security Office, and other senior officials to Singapore ahead of the summit. Tim Shorrock, an American writer on US foreign policy and East Asian politics, told Asia Times that Moon played an indispensable role bringing both leaders to the table.

“Moon was the key driver in both pushing diplomacy with North Korea and getting Pyongyang to talk to the US,” he said. “His overriding interest was preventing a war on the Korean peninsula, especially after it became clear that Washington was complementing some kind of military strike on North Korea.”

Trump optimistic but gaps remain

Ahead of a historic meeting that will be watched by the world, Trump appeared to strike an optimistic tone, telling reporters that his meeting with Kim in Singapore could “work out very nicely,” though notable gaps remain over what denuclearization would entail and the threshold for inclusion of legally-binding security guarantees sought by Pyongyang.

Brian Becker, an American broadcast journalist and anti-war organizer, believes North Korea, despite its recent diplomatic initiatives, would be skeptical of any deal with Washington after the Trump administration’s unilateral withdrawal from the 2015 Joint Comprehensive Plan of Action (JCPOA) nuclear agreement with Iran last month.

Pyongyang’s diplomatic drive, says Becker, seeks to “shift the current narrative” regarding denuclearization with the aim of undermining the US government’s rationale for imposing harsh economic sanctions on the country, as well as toughened United Nations sanctions passed last year, which North Korea’s ally China has, by some accounts, abided by more closely.

“If the Americans appear here as they appear with Iran, the obstacle, while North Korea seems to be the catalyst for a solution,” he says, “then Russia and China will resume a greater economic trade and integration with North Korea and change their position on UN sanctions currently in force.”