US President Donald Trump has become the first sitting US President to step into North Korea.

He met North Korean leader Kim Jong Un at the border between the two Koreas, before stepping over and walking 20 steps into North Korea.

The US President was “proud to step over the line” into North Korea, he said sitting next to North Korean leader.

Trump thanked Kim once again for meeting and added, “When I put out the social media notification if he didn't show up, the press was going to make me look very bad.”

Trump said because Kim showed up, they both looked good.

“This could be a very historic moment and I guess that's what it is,” Trump said. “I think the relationship that we've developed has meant so much to so many people.”

In remarks to press before closing the doors, Kim said he was “very surprised” by Trump's open invitation on Twitter, adding, “I had wanted to meet him again.”

Trump and Kim met inside the Freedom House at the Korean demilitarized zone (DMZ) for roughly 50 minutes, after which the two leaders and South Korean President Moon Jae-in walked back out.

South Korean President Moon Jae-in said the meeting between US President Donald Trump and North Korean leader gives “hope to 80 million Korean people.”

“Through today's meeting, the denuclearization as well as the establishment of peace, that process on the Korean Peninsula, I believe we have just overcome a hill in that overall process. So, the 80 million Korean people on the Korean peninsula have been given hope thanks to today,” Moon said, speaking to the press.

This is a developing story, follow the live update on CNN.com.