WASHINGTON: The US soldier who was held by insurgents for five years after disappearing from his post in Afghanistan has been charged with desertion and “misbehavior before the enemy,” officers said Wednesday.

Sergeant Bowe Bergdahl, 28, was released in May last year in a controversial swap for five Taliban detainees held at the US-run prison at Guantanamo Bay, Cuba.

He could now face a life sentence in a US jail.

The only American in uniform to be held by insurgents in the Afghanistan war, Bergdahl was detained by Taliban-linked Haqqani militants after he went missing from his base in eastern Afghanistan near the Pakistani border in June 2009.

Under the military's code of justice, Bergdahl faces one count of desertion “with intent to shirk important or hazardous duty” and one count of misbehavior that endangers a command, unit or place, Colonel Daniel King told reporters in a televised announcement at Fort Bragg, North Carolina.

Some desertion crimes carry a potential death sentence but authorities said the particular desertion charge outlined against Bergdahl carried a maximum prison sentence of five years, as well as a dishonorable discharge, a reduction in rank and forfeiture of all pay.

The second count of “misbehavior before the enemy” carried a potential life prison sentence, officials said.

The soldier's case will now be subject to a preliminary hearing, in which military authorities will decide whether there is sufficient evidence for a trial.

According to military law, prosecutors will seek to prove that Bergdahl had a duty to defend a unit or place and endangered his fellow soldiers by failing to uphold his duty.

Legal experts have predicted a possible plea agreement in the case, as a trial could prove embarrassing for both sides and expose details of the swap for the Taliban inmates.

Bergdahl's lawyers released a letter Wednesday written by the soldier, in which he describes being tortured, chained to a bed and caged during his detention, US media reported.

Guantanamo question

Some soldiers who served at the same eastern base have alleged that Bergdahl walked out of his unit willingly, putting other troops at risk as they searched for him.

Their account has sparked outrage among some lawmakers and conservative commentators over the prisoner swap.

Bergdahl is being defended by a prominent lawyer and expert on military justice, Eugene Fidell, who teaches at Yale Law School.

Fidell, while declining to discuss the case in depth publicly, has said that Bergdahl was proud to wear the US uniform and has been made a scapegoat by people opposed to closing down the prison in Guantanamo Bay, Cuba.

Republicans say the administration made a dangerous concession by agreeing to the transfer of five senior Taliban figures to Qatar from the Guantanamo prison.

They also say the White House failed to consult with Congress before agreeing the deal and that the transfer of the Taliban detainees has put the United States at risk.

President Barack Obama's administration has defended the handling of the case, saying the government has an obligation to bring all US soldiers home and that military authorities will decide if Bergdahl violated his orders or duties.

“We have a commitment to our men and women serving overseas, or in our military, defending our national security every day, that we will do everything we can to bring them home, and that's what we did in this case,” State Department spokeswoman Jen Psaki told Fox News channel's “The Kelly File.”