Experts have questioned if North Korean leader Kim Jong Un’s private jet can fly direct to Singapore for the summit, considering its age and the fact that it has not been tested for longer-haul journeys. An option might be for Singapore to offer “complimentary flight service as the host of this summit”.

But Mr Shawn Ho, associate research fellow at the S. Rajaratnam School of International Studies in Singapore, said it was “quite unlikely from a political, logistical or cost point of view” for Singapore to do so – on top of hosting the summit.

A more viable option, he said, was for Mr Kim and his entourage to fly on their own to Beijing, and then transfer to another aircraft provided by a third party.

“Maybe the Chinese can provide the plane, so as to show support for North Korea. It will send a political and symbolic message that China is a friend and will be there when North Korea needs them,” he said.