Donald Trump has become the first sitting US president to set foot in North Korea, after meeting Kim Jong-un in the area between the two Koreas.
After posing for handshakes, Mr Trump met the North Korean leader for over an hour in the heavily fortified demilitarised zone (DMZ).
The two men agreed to set up teams to resume stalled nuclear talks.
Their last summit broke down in February with no progress on denuclearisation in North Korea.
In their third face-to-face encounter in just over a year, the two leaders met at the tense area that has divided the peninsula since hostilities in the Korea War ended in 1953.
Numerous previous US presidents have visited the armistice line, largely in a show of US support for the South. But Mr Trump changed the optics of the visit, eschewing binoculars and a bomber jacket for a business suit.
In a meeting apparently arranged after Mr Trump invited Mr Kim on Twitter on Saturday, they shook hands across the demarcation line before Mr Trump briefly crossed into North Korean territory, a symbolic milestone.
"Good to see you again. I never expected to meet you at this place," a smiley Mr Kim told Mr Trump through an interpreter in an encounter broadcast live on international television.
"Big moment... Tremendous progress," Mr Trump said.
Mr Kim, looking relaxed, then crossed into South Korea, and alongside Mr Trump said: "I believe this is an expression of his willingness to eliminate all the unfortunate past and open a new future."
They both walked to a building known as the Freedom House on the South Korean side, where they had private talks.
Speaking alongside Mr Trump in a rare statement to the press, Mr Kim said this was a symbol of their "excellent" relationship.
Calling their friendship "particularly great", Mr Trump said it was a "great day for the world" and that he was "proud to step over the line" between the Koreas. He later said he had invited Mr Kim to visit the US.