North Korean leader Kim Jong-un has been found to be a "trustworthy" person and "very sincere" in implementing the denuclearisation agreement, says South Korean ambassador to Australia Lee Baeksoon.

Key points: North Korea came to the negotiation table to boost and revive their economy

North Korea came to the negotiation table to boost and revive their economy Lee Baeksoon says it's still undecided whether the wargames will be suspended or cancelled

Lee Baeksoon says it's still undecided whether the wargames will be suspended or cancelled He also believes it's too early to tell who the winners and losers are from the summit

Mr Kim pledged to work towards the complete denuclearisation of the Korean Peninsula at the summits held with South Korean President Moon Jae-in in April and US President Donald Trump in Singapore on Tuesday.

While the North Korean regime has reneged on its word before, Mr Lee said North Korea was more sincere than ever before.

He said there were good reasons for North Korea to come to the negotiation table and start the denuclearisation process.

"They need the lifting of the economic sanctions as well as some assistance from the outside because they want to boost their economy and revive their economy," he said.

"I think, actually, they will be very faithful in carrying out their main promises and their pledges.

"Our two leaders — Korean President Moon Jae-in and President Trump, they've met Chairman Kim in person and they found that he's a trustworthy person."

Donald Trump and Kim Jong-un met at the Capella resort on Sentosa Island in Singapore. ( AP: Evan Vucci )

Mr Lee said he believed that this time, Mr Kim and his country would be "very sincere" in implementing their agreement.

"Our whole relationship with North Korea and the Korean Peninsula will be very different to what it has been in the past. We both want to do something," Mr Trump said during the signing ceremony at the summit.

Ambassador Lee Baeksoon, right, received his credentials from Moon Jae-in in February. ( Supplied: Embassy of the Republic of Korea to the Commonwealth of Australia )

Mr Trump also announced a halt to wargames between the US and South Korea and expressed a desire to bring US troops home, which left a former South Korean general "speechless".

However, Mr Lee said it was still undecided whether the military exercises would be suspended or cancelled.

"Our two military authorities are in consultation about the upcoming joint military exercise, so probably there could be some scale down of the military exercise or there could be some suspension of the deployment of strategic asset or there might be some adjustment of the timing," he said.

"But as far as I know it is not actually whole cancellations, the consultation is [still] going on."

Sorry, this video has expired Trump says war games with South Korea have been suspended

'Too early to tell' who the winners and losers are: Lee

North Korea's official media celebrated the major concessions gained from the United States and hailed the summit as a great success.

Front page of the official newspaper Rodong Sinmum the day after the summit. ( Supplied: Rodong Sinmun )

But Mr Lee believed it was still "too early to tell" who the winners and losers were from the summit, adding that the process had just started.

Mr Lee previously praised Mr Trump for taking the initiative with North Korea where previous presidents had not.

"This is very bold diplomacy. I think that kind of diplomacy is possible because of very bold and creative leadership of President Trump," he told the Australian Financial Review earlier this year.

"This issue is so complicated. It has been 25 years since the North Korean nuclear issue popped up and there has been many, many diplomatic efforts and consultations and the Six Party talks, and it didn't go anywhere."

Mr Lee will be speaking more about the future of the Korean Peninsula among other issues at a one-day Symposium held by the Australian National University today.