Ever since the end of WWII, when the Korean Peninsula was removed from Japanese control and divided between Soviet Union and US control, things have been shaky.
Since his election in 2016, Donald Trump has been vocal about his intentions to improve the relationship between the US and North Korea.
His first meeting with North Korean leader King Jong-un was held in Singapore last year.

It ended with hope that changes could be in the future, with North Korea releasing some American prisoners and returning the remains of soldiers who died in the Korean War. Missile tests halted for a time, but recently resumed.
Trump’s second summit with Kim Jong-un in early 2019 didn’t go as well.
Trump walked out of the meeting and things have been at a stalemate ever since.
This latest event took place after Trump tweeted a public invitation to Kim to meet for a handshake in the DMZ while the president was in South Korea.
Kim took him up on his offer and plans were hastily made.
While sitting presidents have visited the DMZ before, it was never with the North Korean leader present.
Some, like Bill Clinton, have made diplomatic visits into the country, but no sitting president has even stepped foot in North Korea since its inception in 1948.
When they met up, Kim was clearly excited that Trump ws there to see him right at the North Korean border.
The event was broadcast live and as the leaders shook hands, Trump asked Kim:
“Would you like me to step across? I am OK with it.”
So he did just that.
He stepped over the demarcation line, which is a low curb that marks the official border of North Korea. Trump then took 20 steps into the country. The leaders shook hands again and patted each other on the backs before returning.
It took only about a minute, but a minute is enough for Trump to make history as the first sitting US President to step on North Korean soil.
Afterwards, Trump and Kim had a meeting in the Freedom House for about an hour.
No substantial agreements were made during their talk, save plans to restart diplomatic talks within the next few weeks.
This matches up with what Trump said in a press conference right before heading to the DMZ.
He’s not in a rush to see huge changes from a single handshake.
“If you’re in a rush, you get yourself in trouble,” he told reporters.
h/t: CNN