Omar Khadr has applied to be transferred to a prison in Canada from Guantánamo Bay to serve the remainder of his sentence for war crimes. Mr. Khadr, a Canadian, was captured in Afghanistan in 2002 after a firefight that left an American sergeant, Christopher Speer, dead. In 2010, a United States military commission sentenced Mr. Khadr, who was 15 at the time of the episode, to 40 years in prison, but he is only required to be imprisoned for a maximum of 8 years under the terms of a plea bargain. The Conservative government had been reluctant to repatriate him. But a government official, who declined to be identified because of restrictions on discussing negotiations with other governments, said American officials had asked for his application to be granted as “a diplomatic favor.”