One of Trump's top North Korea diplomat is retiring this week

His retirement comes just as the Winter Olympics in South Korea ends and North Korea says it would be willing to meet with the US

Joseph Yun, US special representative for North Korea policy, on 25 April 2017. He is set to retire this week. (TORU YAMANAKA/AFP/Getty Images)

One of US President Donald Trump's point men on North Korea is retiring later this week.

Joseph Yun, the special representative for North Korea policy at the US State Department, said: “This is my own personal decision...Secretary [Rex] Tillerson has told me he appreciates my service and did not want me to go, but he accepts it reluctantly," he told the Washington Post.

His retirement comes just as the Winter Olympics in Pyeongchang, South Korea, end during which the two Koreas participated as one team in the opening and closing ceremonies.

One the sidelines, South Korean President Moon Jae-in and North Korean leader Kim Jong-un's sister Kim Yo Jong met face-to-face for the first time.

White House adviser Ivanka Trump was among a US delegation at the closing ceremonies after which the North Korean regime said it would be open to talks with the US.

Mr Moon has been speaking about a "sunshine policy" towards their neighbours to the north through more open economic policy, a platform he ran his presidential campaign on last year.

As the newspaper reported, Mr Yun "was the main person in the State Department dealing with the North Korea problem, and he travelled to Seoul and Tokyo frequently to coordinate with the US allies".

Mr Yun was appointed to his current position in 2016 during the previous administration of Barack Obama and has served the US government for more than 30 years.

He is also leaving the State Department at a time when Mr Trump has yet to nominate a US Ambassador to South Korea that made it past initial review. Victor Cha, who was former President George W Bush's North Korea adviser, was in the running but the administration dropped him as a candidate.

My Yun came into the spotlight when he went to Pyongyang to bring American Otto Warmbier back to the US, the 22-year-old was a University of Virginia student who was held in captivity for 17 months after a tourist visit to North Korea.

Mr Warmbier was released into US custody while he was in a coma. He died a week after his arrival.

The President has had an increasingly tense relationship with Mr Kim and Mr Yun was known for advocating a diplomatic solution to denuclearising the Korean peninsula.

Mr Trump had repeatedly called Mr Kim “Rocket Man” as Mr Kim continued to test missiles dangerously close to US ally Japan last year.

For its part, the United Nations Security Council unanimously passed in December 2017 - including votes from Russia and China who have closer ties to Pyongyang - more sanctions on North Korea, further limiting its oil supplies and slave labour market.

Earlier this week at the Conservative Political Action Conference, Mr Trump announced the "largest ever" sanctions on the country. More than 50 companies, shipping vessels, and trade businesses.

Pyongyang most recently had tested an intercontinental ballistic missile on 29 November that US intelligence officials said would put all of the US mainland within striking range.

The US has declared North Korea a “state sponsor of terrorism” to enact further financial sanctions and also claimed in the President’s National Security Strategy that Pyongyang is developing biological weapons.