Kim Jong Un: North Korea Is 'Very Sorry' for Killing Civil Servant From the South

Mr. Kim’s letter came a day after officials in Seoul said North Koreans shot, killed and burned the body of a 47-year-old South Korean civil servant earlier this week. The unnamed man, who worked at South Korea’s Ministry of Oceans and Fisheries, disappeared from an inspection boat not far from North Korean waters. The South Korean military believes the man told the North Koreans he wanted to defect to the North.

The killing drew condemnations from Seoul and President Trump’s administration in Washington.

The North Korean dictator’s apology is unusual. North Korea typically expresses pity or regret when it kills South Korean civilians—but such correspondences rarely come in writing directly citing an apology from Mr. Kim or his predecessors. It hasn’t apologized for one of its soldiers killing a South Korean civilian visiting a North Korean tourist site in 2008. Pyongyang also hasn’t apologized for a pair of military attacks on South Korea in 2010.

North Korea also hasn’t accepted responsibility for the 2017 death of Otto Warmbier, an American college student who was detained by authorities in Pyongyang. The North released him to Joseph Yun, the U.S.’s envoy for North Korean affairs at the time—in a vegetative state—before he died.

Mr. Kim’s letter suggests he would like to maintain a closeness with Mr. Moon—who was mocked by North Korean state media over the summer—and a desire to keep military tensions lowered, people who watch Pyongyang closely said.

“In order to face Trump in the future, he’s going to need a supportive mediator in Moon,” said Nam Sung-wook, a former head of the South Korean spy agency’s think tank.

In response to the South Korean civil servant’s killing, Mr. Moon ordered South Korean forces to increase their readiness and monitoring of North Korea in the Yellow Sea. Washington expressed support for Seoul and demanded an explanation from Pyongyang about the incident.

In its letter, North Korea disputed some details from the incident provided by the South Korean military on Thursday.

North Korean officials admitted to shooting about 10 rounds at the South Korean civil servant who drifted into the North’s waters, according to the letter. It was some “floating material” that the man had been carrying that was burned, not his body, the North Koreans wrote. The North said it was executing orders established for coronavirus prevention.

After shooting the South Korean man from a distance of about 130 to 160 feet, North Korean officials went to the location where he was last seen, but only found traces of blood, according to the letter.

South Korea’s military previously said North Korean naval officials shot and killed the civil servant at about 9:40 p.m. on Tuesday, meaning visibility would have been impaired.

Tensions between the two Koreas rose in June when North Korea blew up a liaison office that it ran jointly with the South, after which it sent troops to the border. Mr. Moon warned that any armed attack would be met with a response. Within days, Mr. Kim said all military actions would be suspended.

In the weeks before the South Korean man’s killing, relations between the two Koreas were improving, Mr. Moon’s national security adviser said Friday. Messrs. Kim and Moon exchanged two letters this month, the national security adviser said.

In a letter dated Sept. 8, Mr. Moon lauded Mr. Kim’s decision to personally visit flood-stricken regions in the North. Mr. Kim, in a response four days later, said he is confident Mr. Moon will respond to the coronavirus well.

“I will wait for this year’s terrible time to quickly pass, and let the days of the good times come as soon as possible,” Mr. Kim said in his letter to Mr. Moon.

Write to Andrew Jeong at andrew.jeong@wsj.com