The Associated Press could not independently authenticate the emails.
Were Bergdahl to be charged with desertion, the maximum penalty he would face is five years in prison and a dishonorable discharge, if it's proven that he deserted with the intent to avoid hazardous duty or to shirk important service. A case of AWOL, ended by the U.S. apprehending him, would not require proof that he intended to remain away permanently. The maximum punishment for that would be a dishonorable discharge and 18 months' confinement, according to military justice experts.
The U.S. has long been seeking Bergdahl's release, but there was renewed interest in his release as Obama finalized plans to pull nearly all American forces out of Afghanistan by the end of 2016.
Officials said the Taliban signaled to the U.S. in November that they were ready to start new talks on the issue of detainees. After the U.S. received proof that Bergdahl was still alive, indirect talks began, with Qatar sending messages back and forth between the two parties.
The talks intensified about a week ago, officials said, resulting in Bergdahl's release and the transfer of the Afghan detainees.
The senior U.S. official said those U.S. officials involved in the swap decided it could further the effort to reach reconciliation with the Taliban, which they see as a key to achieving a higher level of security in Afghanistan. They acknowledged in their discussions the question of emboldening other insurgent groups to take troops or other Americans prisoner to secure the release of other prisoners, according to the official. The military believed that Bergdahl's status as a prisoner of war obliged doing whatever possible to obtain his release, the official said.
The five Guantanamo detainees departed the base on a U.S. military aircraft Saturday afternoon. Under the conditions of their release, the detainees will be banned from traveling outside of Qatar for at least one year.
Obama and the emir of Qatar spoke last week about the conditions of the release, which have been codified in a memorandum of understanding between the two countries, officials said.
The administration is legally required to notify Congress in advance about plans to release Guantanamo detainees. An administration official said lawmakers were notified only after U.S. officials knew they had Bergdahl, but before the transfers took place.
Two Republican lawmakers said Obama violated U.S. laws when he approved the exchange. Rep. Howard "Buck" McKeon of California and Sen. James Inhofe of Oklahoma said the law required Obama to notify Congress 30 days before any transfer of terrorists from the U.S. detention facility at Guantanamo Bay, Cuba. In response, the White House said that officials considered what they called "unique and exigent circumstances" and decided to go ahead with the transfer in spite of the legal requirement.
The detainees are among the most senior Afghans still held at the prison. They are:
—Abdul Haq Wasiq, who served as the Taliban deputy minister of intelligence
—Mullah Norullah Nori, a senior Taliban commander in the northern city of Mazar-e-Sharif when the Taliban fought U.S. forces in late 2001
—Khairullah Khairkhwa, who served in various Taliban positions including interior minister and had direct ties to Mullah Omar and Osama bin Laden
—Mohammed Nabi, who served as chief of security for the Taliban in Qalat, Afghanistan, and later worked as a radio operator for the Taliban's communications office in Kabul
—Mohammad Fazl, whom Human Rights Watch says could be prosecuted for war crimes for presiding over the mass killing of Shiite Muslims in Afghanistan in 2000 and 2001 as the Taliban sought to consolidate their control over the country.