It was 2013, Kim had been in power for little more than a year following his father's death, and international media had been invited to Pyongyang for the 60th anniversary of the end of the Korean War.

After a ceremony at a museum to the conflict, the North's leader suddenly appeared in a corridor, sending the assembled journalists scrambling.

"Kim Jong Un! Channel Four News, UK!" a reporter shouted as he passed. "What message are you trying to send to the West?"

Kim moved on down the passageway, surrounded by aides, leaving the cameraman with a shot of the back of his head.

Six years later, and after several summits with the presidents of China, South Korea and the US, the demeanour of the North's leader has changed.

Domestically, Pyongyang closely controls all the leader's appearances and depictions.

Frequently state television does not even broadcast natural sound from his events, with a newsreader instead reading out a dispatch from the official KCNA news agency over still or video images.

But in Hanoi for his second summit with US President Donald Trump, Kim was relaxed enough to answer a question from a foreign reporter -- believed to be unprecedented.

As the two men sat down ahead of a one-on-one session, a Washington Post reporter asked if he was confident he could reach a deal with Trump.

Kim leaned back slightly to listen to the whispered words of his translator.

"Well it's too early to tell," he responded. "But I wouldn't say that I'm pessimistic."

"For what I feel right now, I do have a feeling that good results will come out."

He answered more shouted questions at other media opportunities later in the day -- but observers cautioned against interpreting it as representing a new openness on the part of Pyongyang.