It's critical Australia maintains pressure on North Korea until talks about denuclearisation turn to action, Malcolm Turnbull says.
He's positive about what could be a historic summit between the rogue nation and the United States, but says it must be approached with caution as there's been "many false dawns before".
Kim Jong-un is expected to meet Donald Trump sometime before May in what would be a first-time meeting between a North Korean leader and a sitting US president.
"I emphasise those sanctions must remain in full force, rigorously enforced, until such time as the regime does start to denuclearise," Mr Turnbull said in McLaren Vale, South Australia on Saturday.
"It has got to make a commitment and demonstrate its commitment by actions to remove its illegal, dangerous and reckless nuclear capability and threat."
Mr Turnbull said it was sanctions along with a strong stand by Mr Trump that had brought President Kim to the table.
He said time would tell if this latest plan for talks was another false dawn or something more.
Labor's defence spokesman Richard Marles agreed existing sanctions had bitten North Korea.
"To that end, it's really critical the campaign of maximum pressure through sanctions is maintained and there's no letting up on that," he said.
"If anything is going to change North Korean behaviour, it is that."
President Kim has committed to denuclearisation and to suspending nuclear or missile tests, South Korea's National Security Office head Chung Eui-yong told reporters at the White House on Thursday.
White House spokeswoman Sarah Sanders said Mr Trump "will accept the invitation to meet with Kim Jong-un at a place and time to be determined".
But the US also says the meeting won't take place unless there's concrete action to match North Korea's words and rhetoric.
It's expected the summit could take place in Panmunjom, the truce village in the demilitarised zone between North and South Korea.
Switzerland has also offered to host, while former prime minister Kevin Rudd suggested Beijing as a possible host, though that would require persuading President Kim he's safe to leave the country.
Mr Rudd is approaching the meeting with a degree of scepticism, but said it had the opportunity to rewrite history.
However, he said it needed the right preparation, including around definitions of denuclearisation and what it would mean for future missile and nuclear testing programs.
Suggestions are Mr Trump isn't approaching the idea of a summit with the caution and preparation needed, Mr Rudd said, but acknowledged the president had his own way of doing things.
"He runs his own remarkable diplomatic style and, if you like, he's meeting another leader in North Korea who has his own remarkable style as well," he told ABC on Saturday.
"This could end spectacularly well, or it could end spectacularly badly."