Seoul, South Korea CNN  — 

North Korean leader Kim Jong Un has apologized for the death of a South Korean government worker who was shot dead by North Korean troops after crossing a maritime border between the two countries.

In a letter sent to South Korea’s Blue House Friday morning, North Korea said units responded to a call that an unidentified male was found floating on an object in the sea. The letter claims about 10 rounds were fired at the man after he did not comply with a soldier’s demand to identify himself and subsequent warning shots.

North Korea says only a pool of blood remained on the floating object after the shots were fired. After soldiers presumed the man to be dead, they burned the floating object on site per North Korea’s Covid-19 disease prevention measures.

“Chairman Kim Jong Un asked to convey that he feels very sorry that instead of giving aid to our compatriots in the South who is struggling with Covid epidemic, we have given President Moon and our compatriots in the South a great disappointment with this unseen misfortune in our sea,” the letter read, according to the Blue House.

The statement added that North Korea has strengthened its maritime surveillance and apologized for “an incident that will clearly negatively impact inter-Korean relation.”

Apologies from Kim are rare, especially when it comes to apparent mistakes by the country’s military.

According to Lt. Gen. Ahn Young-ho, a top official with South Korea’s Joint Chiefs of Staff, a worker with the Ministry of Maritime Affairs and Fisheries went missing in waters 1.9 kilometers (1.2 miles) south of the Yeonpyeong Islands on September 21.

South Korean defense officials previously said they believed the man was in the process of attempting to defect to North Korea. In a statement Thursday, the South Korean military said it “strongly condemns the North’s atrocities” and urged Pyongyang to provide an explanation and punish those responsible.

Tensions have been rising between North and South Korea since communication between the two sides was cut off in June, when Pyongyang first closed and then blew up a joint liaison office in Kaesong, a city on the northern side of the border.

The deterioration in relations came after a years-long rapprochement led by South Korean President Moon Jae-in resulted in historic meetings between himself and North Korean leader Kim Jong Un, as well as summits between Kim and US President Donald Trump.

But those meetings ultimately did not deliver significant results for all sides, and North Korea has taken an increasingly strident tone towards its southern neighbor, a shift in stance that has come as Kim’s sister, Kim Yo Jong, moved into a more influential position in the North Korean regime.

Speaking Thursday, South Korean Foreign Minister Kang Kyung-hwa said that the offer of dialogue towards North Korea remains open, and Seoul is ready to engage with Pyongyang.

In the weeks prior to the shooting, Kim had exchanged letters with South Korean President Moon Jae-in, the Blue House said.