There's an upbeat tone that a formal declaration ending the Korean War could be made at the Hanoi summit this week.
Hopes that US President Donald Trump and North Korean leader Kim Jong-un will formally declare an end to the 1950-53 Korean War at the Hanoi summit rose Monday, after South Korea said the two leaders could reach an agreement.
The devastating conflict between communist North Korea, backed by China, and the capitalist South, aided by the United States, ended with an armistice rather than a peace treaty, leaving Pyongyang and Washington still technically at war.
"I believe that the possibility is there," the South's presidential Blue House spokesman Kim Eui-kyeom told reporters about a formal declaration.
"There is no way of knowing what kind of declaration it might be, but I believe the US and North Korea may reach an agreement."
President Moon Jae-in said in October "it was only a matter of time" before Washington and Pyongyang declared an end to the war.
The US has also struck an upbeat tone. Stephen Biegun, the US special envoy for North Korea, said earlier this month that Trump was "ready to end this war", fuelling speculation that the formal end of the conflict may be near.
Kim, the leader of North Korea, is due to meet the US president in the Vietnamese capital on Wednesday and Thursday, where it is hoped the pair will make progress in talks on denuclearisation, and a possible peace treaty.
But Blue House spokesman Kim said even if the US and North Korean leaders declare the end of the Korean War, a formal peace treaty will likely be signed at the "last stage of the denuclearisation process" of the Korean peninsula -- and may take a long time to materialise.
"A peace treaty and a declaration of end of war are different," he said, adding that the treaty must be a "multilateral effort" involving South Korea and China.
North Korea, the US-led United Nations Command and China were all signatories to the armistice.
The Hanoi summit comes after Trump and Kim met in June in Singapore, producing a vaguely worded agreement on denuclearisation, but progress has since stalled, with the two sides disagreeing over what the agreement meant.
Observers say tangible progress is needed in Hanoi to avoid the talks being dismissed as a publicity stunt.
Trump in no rush to strike nuclear deal
President Trump says he would be happy as long as North Korea maintains its pause on weapons testing, and he is in no rush to strike a nuclear deal with Kim Jong-un.
US Democratic senators and security officials have warned Trump against cutting a deal that would do little to curb North Korea's nuclear ambitions.
As Kim made his way across China by train for the summit, North Korean state media warned Trump not to listen to US critics who it said were disrupting efforts to improve ties.
Trump, speaking in Washington on the eve of his departure for Vietnam, said he believed he saw eye to eye with Kim and that they had developed "a very, very good relationship".
"I'm not in a rush. I don't want to rush anybody," Trump said. "I just don't want testing. As long as there's no testing, we're happy."
North Korea conducted its last nuclear test, its sixth, in September 2017. It last tested an intercontinental ballistic missile in November 2017.
The Trump administration has pressed the North to give up the nuclear weapons programme, which combined with its missile capabilities, pose a threat to the US, before it can expect any concessions.
But in recent days, Trump has signalled a possible softening, saying he would love to be able to remove sanctions if there is meaningful progress on denuclearisation.
Trump said he and Kim expected to make further progress at the summit and again held out the promise that denuclearisation would help North Korea develop its economy.
He scoffed at critics of his handling of North Korea, and added that Chinese President Xi Jinping has been supportive of US efforts on North Korea.
Additional reporting AAP