The US has secured the release of an American soldier who sprinted across a heavily fortified border into North Korea more than two months ago, the White House has announced.

US ally Sweden and rival China helped with the transfer.

Left unanswered were questions about why Pyongyang — which has tense relations with Washington over the North’s nuclear programme, support for Russia’s war in Ukraine and other issues — has agreed to turn him over and why the soldier fled in the first place.

North Korea abruptly announced earlier on Wednesday that it would deport Private Travis King — despite some expecting the North to drag out his detention in hopes of squeezing concessions from Washington at a time of high tensions between the two countries.

“US officials have secured the return of Private Travis King from the Democratic People’s Republic of Korea,” White House national security adviser Jake Sullivan said in a statement.

“We appreciate the dedication of the interagency team that has worked tirelessly out of concern for Private King’s wellbeing.”

Officials said they did not know exactly why North Korea decided to expel King but suspected Pyongyang determined that as a low-ranking serviceman he had no real value in terms of either leverage or information.

One official, who was not authorised to comment and requested anonymity, said the North Koreans may have decided that the 23-year-old was more trouble to keep than to release him.

Swedish officials took King to the Chinese border, where he was met by the US ambassador to China Nicholas Burns, the Swedish ambassador to China and at least one US Defence Department official.

Officials from US President Joe Biden’s administration insisted they provided no concessions to North Korea to secure the soldier’s release.

“We thank the government of Sweden for its diplomatic role serving as the protecting power for the United States in the DPRK and the government of the People’s Republic of China for its assistance in facilitating the transit of Private King,” Mr Sullivan added.

King was being flown to a US military base in South Korea before being returned to the US.

His expulsion almost certainly does not end his troubles or ensure the sort of celebratory homecoming that has accompanied the releases of other detained Americans.

And there remain unanswered questions about the episode, including why King went to North Korea in the first place.

His fate in the US remains uncertain, having been declared absent without leave by the government.

That can mean punishment by time in military jail, forfeiture of pay or a dishonourable discharge.

In the near term, officials said their focus will be on helping King reintegrate into US society upon his return, including helping him address mental and emotional concerns, according to a senior Biden administration official who briefed reporters on the transfer.

The soldier was in “good spirits and good health” upon his release, according to one senior administration official.

He was to be taken to Brooke Army Medical Centre at Fort Sam Houston in Texas and expected to arrive overnight, officials said.

King, who had served in South Korea, ran into North Korea while on a civilian tour of a border village on July 18, becoming the first American confirmed to be detained in the North in nearly five years.

At the time he crossed the border, King was supposed to be heading to Fort Bliss, Texas, following his release from prison in South Korea after an assault conviction.

Sweden was the chief interlocutor with North Korea on the transfer, while China helped facilitate his transfer, administration officials said.

Biden administration officials expressed gratitude for China’s assistance with the transfer but underscored that Beijing did not play a mediating role in securing King’s release.

The US first learned through Swedish officials earlier this month that North Korea was looking to kick out King.

That information accelerated the effort to release King with Sweden acting on the US’s behalf in its talks with the North, an official said.

On Wednesday, the North’s official Korean Central News Agency reported that authorities had finished their questioning of King.

It said he confessed to illegally entering the North because he harboured “ill feeling against inhuman maltreatment and racial discrimination” within the US army and was “disillusioned about the unequal US society”.

It had attributed similar comments to King before and verifying their authenticity is impossible.

Some previous foreign detainees have said after their releases that declarations of guilt while in North Korean custody were made under coercion.

The White House did not address the North Korean state media reports that King fled because of his dismay about racial discrimination and inequality in the military and US society.

One senior administration official said King was “very happy” to be on his way back to the US.