Private 2nd Class King, 23, had fled across the border in July after joining a Demilitarised Zone (DMZ) border tour.
On Wednesday, following his expulsion, he was flown to a US military installation.
The 23-year-old’s crossing came during a particularly tense time with the North, one of the world’s most isolated states. The US tells its citizens not to go there.
What do we know about his deportation?
A senior US administration official said that after months of “intense diplomacy”, Pvt King was returned to US hands and had spoken to his family.
“We can confirm Pvt King is very happy to be on his way home and he is very much looking forward to reuniting with his family,” the official said.
“We are going to guide him through a reintegration process that will address any medical and emotional concerns and ensure we get him in a good place to reunite with his family.”
The process of safely returning the soldier began earlier in September, when the US learned that North Korea intended to release Pvt King.
Swedish officials then travelled to North Korea and brought Pvt King to its border with China, where he was handed over to US officials.
China played a “constructive role”, but “did not mediate”, the official added. “All these pieces had to come together quickly.”
As the US and North Korea have no diplomatic relations, Sweden’s embassy in Pyongyang has traditionally negotiated on behalf of the US.
A Swedish embassy spokesman confirmed that the country had acted “within its role as a protective power” for the US in North Korea during the King case.
Shortly after Pvt King left Chinese airspace, US National Security Advisor Jake Sullivan thanked both the Swedish and Chinese governments for their support in returning him.
How did he get across the border in the first place?
At the time of the incident, Pvt King was being escorted back to the US to face disciplinary action.
But he did not board the plane. Instead, he reportedly arrived at the boarding gate at Incheon Airport alone, as military police officers were not allowed to accompany him all the way to the plane.
At the gate, he reportedly approached an American Airlines official, claiming his passport had gone missing. An airline employee then escorted him out of the departures area.
He then made his way out of the terminal to the border crossing about 54km (34 miles) away.
An eyewitness on the same border tour described hearing the soldier laughing loudly before making a run.
What do we know about the soldier?
Pvt King has been in the Army since January 2021. He is a cavalry scout – a reconnaissance specialist – originally assigned to an element of the army’s 1st Armoured Division on a rotation with the US military in South Korea.
He had been held in a detention facility in South Korea’s capital, Seoul, after getting into fights. He was reportedly investigated for assault in September 2022.
Local media reports say he was suspected of punching a Korean national in a Seoul nightclub.
He was also fined 5m won (£3,000; $3,950) for “repeatedly kicking” the back door of a police car and screaming “foul language” at the officers trying to apprehend him.
Local reports quoting officials said he was released on 10 July after serving two months in jail on assault charges.
He was released to Camp Humphreys – an army base in South Korea – for out-processing.
He was later escorted to the airport in Incheon, Seoul, for a flight back to the United States, where he was to face disciplinary action.
A US defence official confirmed Pvt King had been due to travel to Fort Bliss in Texas, where he was to be administratively separated from the army.
A defence official said the soldier had “wilfully” crossed the border.
What has his family said?
Pvt King’s mother, Claudine Gates, told ABC News in July she could not imagine her son doing such a thing. He “had to be out of his mind”, she said.
Carl Gates, an uncle, told the Daily Beast that Pvt King had been “breaking down” emotionally over the death of his 7-year-old cousin.
Pvt King began acting “reckless” and “crazy” around the time of his cousin’s death in February, the uncle said.
Did the soldier plan his move?
It is possible the soldier’s move was planned.
The host of the North Korea podcast, Jacco Zwetsloot, worked for a tour company in 2012 that took US soldiers to the JSA. He says there is “no way this person could escape from the airport one day and book on to one of these tours the next”.
He explains that it usually takes three days to be authorised to go on one of these trips. You need to submit your passport number and military ID to the UN Command, which operates the area.
“When I was leading the tours, we had to change the turnaround time from 48 to 72 hours because there were too many mistakes,” he says.
Also, since the pandemic, it has been much more difficult to get on these tours. They only restarted recently and it seems there are just two companies offering tours to foreigners. To book this would have required research and planning.
What happened to Americans detained by North Korea in the past?
US citizens have been detained there several times since 1996. They included tourists, scholars and journalists.
In July 2017, the US government banned US citizens from visiting the country – a move that has since been extended until at least August this year.
US prisoners have typically been treated brutally in North Korean prisons.