Singapore is paying the hotel bill for North Korean leader Kim Jong Un and his contingent, Foreign Minister Vivian Balakrishnan said yesterday.

"It is hospitality that we would have offered them, and as Chairman Kim said... he would have liked to have come to Singapore anyway, with or without the summit," Dr Balakrishnan said in an interview with the BBC.

Mr Kim, who is Chairman of North Korea's State Affairs Commission, arrived in Singapore on Sunday for a historic summit today with United States President Donald Trump to discuss possible denuclearisation efforts.

The North Korean delegation is staying at The St Regis Singapore.

Dr Balakrishnan also said the expenditure is part of the $20 million that Singapore is spending on the summit.

The BBC interviewer, noting that Mr Kim is notoriously paranoid about his safety, asked what Singapore did to reassure him.

Dr Balakrishnan said the North Korean advance team came to Singapore, walked the grounds, checked the hotels and met local officials. "I think over the weeks that they spent with us, they gained greater confidence that we are sort of no-nonsense but efficient people," he said. "We are good for our word, we are meticulous, we pay attention to details - every smallest detail. "

Today's summit comes after what Dr Balakrishnan described as 70 years of suspicion, war and diplomatic failures. "This is not the way conventional diplomacy would have been conducted, but perhaps you need two very unconventional leaders to have brought us to this stage," he said.

Still, he noted that decades of tension cannot be resolved in one meeting, although, based on his interactions with their staff and meeting them personally, "both are supremely confident, both are hopeful".

Asked what he thought brought Mr Kim to the negotiating table, Dr Balakrishnan listed a number of factors and added that his views were "purely speculative".

These include Mr Kim feeling he has achieved his military objectives and that it is "time for economic development".

Also, Mr Trump has "been willing to break the taboos and boundaries of the past, and give him an opportunity to meet face to face as equals", said Dr Balakrishnan.

"The stars are aligned, but we must avoid wishful optimism... Let's just have hope based on a realistic assessment of what could or may not happen."