The American soldier who crossed into North Korea in July has been charged with desertion, assaulting fellow soldiers and soliciting child pornography, according to United States media reports on Thursday.

The US Army has brought eight charges, including providing false statements and illegal possession of alcohol, against Travis King, who had been stationed in South Korea, according to a document cited by multiple US outlets.

After a drunken bar fight and a stay in a South Korean jail, the Private Second Class was to fly back to Texas for disciplinary hearings but instead walked out of the Seoul-area airport, joined a Demilitarized Zone sightseeing trip and slipped over the massively fortified border where he was detained by the communist North's authorities.

Pyongyang had said that King had defected to North Korea to escape "mistreatment and racial discrimination in the US Army."

But after completing its investigation, North Korea "decided to expel" King in September for illegally intruding into its territory.

Deputy Pentagon Press Secretary Sabrina Singh said King would go through a "reintegration program" involving medical screenings and mental health assessments after he was returned to the US.