North Korea's apology over its recent fatal shooting of a South Korean government official is a "helpful step," the US State Department said Friday, while reaffirming its support for South Korea's condemnation and demand for a full explanation.

The reaction came shortly after North Korean leader Kim Jong-un said he felt "very sorry" in a message sent to South Korea.

"We understand that the DPRK has conveyed an explanation and apology to the ROK. This is a helpful step," a spokesperson from the US Department of State told Yonhap News Agency, while speaking on condition of anonymity.

DPRK stands for North Korea's official name, the Democratic People's Republic of Korea.

It marked a very rare occasion where the North's highest leadership apologized for an incident that took place between the divided Koreas.

The communist state shot and killed a female South Korean tourist at a resort in Mount Kumgang in 2008, but it has yet to offer an apology.

In the message, sent Friday (Seoul time), the North Korean leader said this week's shooting incident near the de facto inter-Korean maritime border should not have occurred and that he was sorry to have "disappointed" the South Korean president and the people of South Korea.

It also offered an account of the incident that took place Tuesday when North Korean guards shot and killed a 47-year-old South Korean, affiliated with the maritime ministry, who was drifting in the waters, according to Seoul's National Intelligence Service.

Earlier reports had suggested the North may have cremated the body of the deceased. North Korea denied the allegation, saying the body was nowhere to be found.

The US State Department offered condolences to the family of the deceased.

"We offer our deepest condolences to the friends and family of the South Korean official who was killed," the spokesperson said.

The department also reaffirmed its support for South Korea in seeking full details of the incident.

"We fully support our ROK ally's condemnation of this act and the ROK's call for a full explanation from the DPRK," the statement said, referring to South Korea by its official name, the Republic of Korea.

US experts viewed North Korea's apology as an unexpected move that could work positively toward improving North Korea's relationship with South Korea and others.

"North Korea's apology is a rare occurrence," said Bruce Klingner, a senior researcher at the Washington-based Heritage Foundation.

"While much will be made of whether the North's apology portends an improvement in inter-Korean relations, more positive actions by Pyongyang will be necessary," he added.

Harry Kazianis, senior director of Korean studies at a Washington-based policy think tank, the Institute for the National Interest, noted Kim's apology may have shown a "human" side of him that may indicate possible concessions in denuclearization talks.

"I do think Kim has shown to the South Korean people a more human and vulnerable side," said Kazianis.

"While we should clearly understand who we are dealing with -- this is the man who executed his uncle with anti-aircraft guns and poisoned his half-brother with VX -- there is some human in him.

And that means negotiation and compromise are certainly a possibility," he added.

Still, the US expert noted Kim's apology may have been derived by his need to keep his country from further isolation.

"North Korea and especially Kim Jong-un personally are under immense strain and pressure. Pyongyang is not only having to deal with the sting of economic sanctions but also typhoon damage, agricultural shortages and also COVID-19. The Kim regime, at least for now, surely does not want to have any more pressure or troubles, or lose President Moon as a partner in peace," he said. (Yonhap)