A former child soldier has greeted prospective jurors at the start of his trial, billed by defence lawyers as the first war-crimes prosecution of a former child soldier since the Second World War.
Omar Khadr, the Toronto-born son of an alleged al-Qaida financier, is the youngest prisoner at the US detention camp in Guantanamo Bay, Cuba, and the only remaining Westerner.
He was 15 when he allegedly hurled a grenade that killed a US Delta Force soldier during a gun battle in Afghanistan in 2002.
The trial will be closely watched as the first under President Barack Obama, whose administration is weighing whether to use the Guantanamo courts as a venue for dozens of other detainees - including major figures such as the self-professed mastermind of the September 11 attacks and four alleged henchmen.
The Khadr case has been held up by legal wrangling at several versions of the tribunal system since he made his first appearance in the courthouse overlooking the Caribbean Sea in 2006.
The Canadian, now a bearded man of 23, traded his prison jumpsuit for a grey suit before the start of jury selection. As his Pentagon-appointed attorney introduced him to the pool of 15 US military officers, Khadr stood and said to them in English: "How are you?"
Defence lawyers and prosecutors spent much of the day asking prospective jurors their opinions on matters including the significance of a juvenile offender's age and the treatment of detainees at Guantanamo Bay.
Advocates have argued that prosecuting somebody who was so young at the time of the alleged offence would violate international treaties protecting child soldiers. But the court sided with prosecutors, who argued that such protections do not apply to Khadr. But the judge, Army Col Pat Parrish, interrupted a prosecutor's questioning to say jurors could consider his age in deciding whether he intended to commit a crime.
Once a panel of at least five officers is seated, opening arguments are planned in a trial expected to last roughly three weeks. Khadr has pleaded not guilty a total of five charges including murder for allegedly killing US Army Sgt 1st Class Christopher Speer, 28, of Albuquerque, New Mexico, after a battle at an al-Qaida compound on July 27, 2002. Military prosecutors say he also planted explosive devices to kill coalition forces and spied on U.S. troops. He faces a maximum life sentence if convicted.
Defence lawyers say Khadr was himself a victim, forced into war by a family with close ties to Osama bin Laden. His father, Ahmed Said Khadr, was an Egyptian-born Canadian citizen and alleged militant killed in 2003 when a Pakistani military helicopter shelled the house where he was staying with senior al-Qaida operatives.