When US President Donald Trump confirmed in the early morning of June 2 (Singapore time) that the on-again, off-again summit with North Korean leader Kim Jong Un would go ahead as planned, many involved in helping to facilitate the summit heaved a sigh of relief.

On one hand, they knew that life for the next two weeks would be turned upside down.

But on the other hand, the thousands of hours devoted to preparing for the hosting of such a high-profile meeting would not have gone to waste.

Singapore had been linked as a possible host for the June 12 meeting as early as March. Even before Mr Trump first confirmed the Republic as the host on May 10, the Singapore government machinery had already rolled into action.

An inter-agency task force was put together, comprising senior foreign affairs and home affairs officials, as well as representatives from agencies including the Ministry of Defence, the Transport Ministry and the Ministry of Health.

Home Affairs and Law Minister K. Shanmugam told the media last Friday that Singapore had to grapple with significant security and logistical challenges to host Mr Trump and Mr Kim, who is Chairman of the State Affairs Commission.

"We are talking about two weeks. It usually takes months to prepare for something like this," he said.

Sources told The Straits Times that even when Mr Trump called off the summit on May 24, preparations still continued.

Given the uncertainty over the summit, much of the work took place behind closed doors.

At the Ministry of Foreign Affairs (MFA) building in Sherwood Road, teams were put in place to facilitate planning and negotiations between the United States and North Korea.

Singapore had also hosted the landmark 2015 summit between China's President Xi Jinping and Taiwan's then President Ma Ying-jeou, and the expectation was for Singapore's Foreign Service to draw from that experience.

MFA officials assisted the advance teams of both countries when Mr Kim Chang Son, the de facto chief of staff of Mr Kim, had pre-summit meetings with White House deputy chief of staff Joe Hagin to iron out the logistical details of the visit two weeks ago.

Shortly after the meeting, which took place alongside others in New York and North Korea involving key officials of both nations, the summit was resurrected.

Said a senior public servant who declined to be named: "Down the ranks, thousands of civil servants have been sitting in daily meetings and briefings to iron out all kinds of details, including protocol, ground security, air movements, road closures and emergency procedures, should any hiccups occur."

The international media will be focusing the world's attention on Singapore. And while they will capture every smile and handshake that the two leaders will exchange, any security issues will also make headlines.

Between the Singapore Police Force and the Singapore Armed Forces (SAF), there will be thousands of boots on the ground providing security and traffic control operations.

There will also be security personnel looking to ensure the safety of the two leaders in the air and around the waters off Sentosa, which will host the summit.

But planning was challenging, with the meeting venue not decided until about a week before the summit, sources say.

While the Capella Singapore hotel in Sentosa will provide a scenic setting for the meeting, experts cautioned that protecting it will require more security resources than if the event was held at the Shangri-La, the other venue contender.

With more than 50,000 tourists and local residents in Sentosa on an average day - the number is significantly higher during the June school holidays - screening those entering the island is also going to be a challenge, they added.

Then there are preparations ensuring the two leaders' safety as they make their way to Sentosa.

Arrangements have been made to make Mr Trump's journey from Shangri-La Hotel to Sentosa seamless. Likewise for Mr Kim, who will depart from The St Regis Singapore.

Apart from routes being kept a secret, overhead bridges will also be locked down as the respective convoys make their way across the city.

To ensure there is enough manpower for such a massive operation, police officers were told weeks earlier that all leave would be frozen during the visit period. Operationally ready national servicemen were alerted to be on standby.

In 2006, when the police staged a large-scale security operation during the International Monetary Fund-World Bank meetings here, regular and auxiliary police officers, along with some 23,000 national servicemen, were deployed.

Security then was beefed up by SAF personnel, as well as officers from the Gurkha Contingent and Volunteer Special Constabulary.

With the global media focused on the June 12 summit, the Ministry of Communications and Information also had its hands full, processing pass applications from thousands of local and international journalists.

More than 2,500 journalists expected to cover the summit have been working since June 10 from the F1 Pit Building, where an International Media Centre has been set up. Even before that, members of the foreign media had started arriving. Some came as early as two weeks before the summit, when the American and North Korean advance parties arrived.

On the commercial front, staff at Singapore's top hotels have also been in overdrive the last few weeks, first scrambling to block rooms, releasing some after the meeting was declared cancelled, only to reclaim them to cater to the delegations of both nations, as well as the growing list of media representatives.

Apart from the Capella, Shangri-La, St Regis and Fullerton, identified as places to house the delegations, other hotels in the Marina Bay and Orchard Road areas were kept busy handling queries on room availability from the foreign media.

Food and beverage outlets across Singapore are also rolling out themed meals and drinks with American and Korean influences.

At the Singapore Flyer, several businesses that have extended their hours and increased staff strength are also offering promotions for the public and members of the media. Gourmet burger restaurant Wolf Burgers has introduced a "Burger for World Peace" - a riff on the American Philly cheesesteak with a Korean touch. At the Royal Plaza on Scotts, free Trump-Kim burgers will be given out at noon and 6pm on the day of the summit.

The meeting has also attracted Trump and Kim impersonators to Singapore, some of whom even engaged media agencies to plan their public interactions.

Despite the short runway for preparing for the summit, Dr Bilveer Singh, adjunct senior fellow at the S. Rajaratnam School of International Studies, has no doubt that Singapore will hold its own.

He said: "We are an event state - 365 days a year, event after event, big and small. So while the short runway is unprecedented, the Singapore government machinery is always well prepared and ready for all systems go. I have no doubt that Singapore will more than rise to the challenge of hosting this historic summit."