PANMUNJOM — Donald Trump stepped onto North Korean soil Sunday as he met Pyongyang's leader Kim Jong Un in the Demilitarized Zone dividing the peninsula, in a symbolic diplomatic spectacle and a first for any American president.

After shaking hands with Kim over the line that marks where their two countries and their allies fought each other to a standstill in the 1950-53 Korean War, Trump walked for several steps into North Korean territory, before another handshake.

The two men then walked into Seoul's territory together – pausing on the line for photographers – where they were joined by South Korean President Moon Jae-in.

"It's a great day for the world and it's an honour for me to be here," Trump said. "A lot of great things are happening.”

As the two men held historic discussions, Trump signalled a willingness to invite Kim Jong Un on a visit to Washington.

"I would invite him right now, to the White House," Trump said, while North Korean leader said that his "wonderful" relationship with US President Donald Trump would enable the two longtime enemies to get over obstructions, with their nuclear talks at a stalemate.

"I am convinced our relationship will enable us to overcome barriers standing in the way," said Kim, adding that their close ties enabled a meeting to happen "just overnight".

The impromptu meeting in the DMZ – which came after Trump issued an invitation on Twitter on Saturday – comes with negotiations between Pyongyang and Washington over the North's nuclear arsenal at a deadlock.

Earlier Trump said the two would "just shake hands quickly and say hello because we haven't seen each other since Việt Nam", Trump said earlier.

Their first summit took place in a blaze of publicity in Singapore last year but produced a vaguely-worded pledge about denuclearisation, and a second meeting in Việt Nam in February intended to put flesh on those bones broke up without agreement.

North Korea's leader Kim Jong Un (L) and US President Donald Trump attend a meeting on the south side of the Military Demarcation Line that divides North and South Korea, in the Joint Security Area (JSA) of Panmunjom in the Demilitarized zone (DMZ) on June 30, 2019. — AFP/VNA Photo

Contact between the two sides has since been minimal – with Pyongyang issuing frequent criticisms of the US position – but the two leaders have exchanged a series of letters and Trump turned to Twitter on Saturday to issue his offer.

"If Chairman Kim of North Korea sees this, I would meet him at the Border/DMZ just to shake his hand and say Hello(?)!," he wrote from from Osaka in Japan, where he was attending a G20 summit before flying to Seoul.

In an unusually fast and public response, within hours of Trump's tweet the North's official KCNA news agency quoted Vice Foreign Minister Choe Son Hui as saying the offer was "a very interesting suggestion".

Trump's entry onto North Korean soil is a dramatic re-enactment of the extraordinary scene last year when the young leader invited South Korean President Moon Jae-in to walk over the Military Demarcation Line that divides the Koreas.

Moon – who seized on last year's Winter Olympics to broker the process between Pyongyang and Washington, after tensions soared in 2017 amid missile and nuclear tests and mutual insults – accompanied Trump to the DMZ.

"The leaders of the US and the North will have a handshake for peace at Panmunjom, the symbol of division, for the first time," Moon said, referring to the "truce village" in the DMZ. — AFP