(CNN) -- The United States found "an opening" and acted quickly to save U.S. Army Sgt. Bowe Bergdahl's life, Defense Secretary Chuck Hagel said Sunday.
"We believed that the information we had, the intelligence we had, was such that Sgt. Bergdahl's safety and health were both in jeopardy and in particular his health deteriorating," Hagel said. "It was our judgment that if we could find an opening and move very quickly with that opening, that we needed to get him out of there essentially to save his life. I know President Obama feels very strongly about that, I do as well."
Bergdahl, the last American soldier held captive from the Iraq and Afghanistan conflicts, is on a long journey home after being freed Saturday in a prisoner exchange.
He arrived Sunday at Landstuhl Regional Medical Center in Germany, a U.S. defense official said.
The 28-year-old Idaho native, who spent five years in the hands of Afghan militants, was expected to undergo medical treatment and be debriefed at Landstuhl, a massive facility that treats serious war injuries from the Iraq and Afghanistan conflicts.
His "reintegration process" will include "time for him to tell his story, decompress, and to reconnect with his family through telephone calls and video conferences."
A senior defense official said Bergdahl would likely go to Brooke Medical Center in San Antonio when he is ready to leave Landstuhl. It's unclear if his parents will see Bergdahl first in Germany or Texas, a defense official said.
U.S. special operations forces recovered Bergdahl without incident early Saturday local time at a "pickup" point in eastern Afghanistan, near the border with Pakistan, a senior Department of Defense official told CNN. American officials said the government of Qatar brokered the deal, in which five Guantanamo detainees were swapped for Bergdahl.
Obama, flanked by Bergdahl's parents at the White House on Saturday, praised the diplomatic officials and troops who helped secure Bergdahl's release.
"While Bowe was gone, he was never forgotten," the President said.
Bergdahl's mother, Jani, said, "We will continue to stay strong for Bowe while he recovers."
His father, Bob Bergdahl, spoke a few phrases in Pashtun, saying that his son is having trouble speaking English after his captivity in Afghanistan, according to a military press service.
"The complicated nature of this recovery will never really be comprehended," his father said.
A senior defense official confirmed Bowe Bergdahl is having trouble speaking English but the reasons for that were not clear, given the trauma he's been through.
Also unclear is how Bergdahl fell into the hands of the Afghan militants. When a reporter asked if Bergdahl had deserted, Hagel didn't answer directly.
"Our first priority is assuring his well-being and his health and getting him reunited with his family," he said. "Other circumstances that may develop, they will be dealt with later."
'Our only son'
The U.S. government secured Bergdahl's freedom in exchange for the release to the Taliban of five of its members detained at Guantanamo Bay.
After Bergdahl was handed over, a series of secret procedures was set in motion so each side knew the other was living up to the bargain. Qatari officials were already at Guantanamo and took custody of the detainees.
A U.S. Air Force aircraft carrying them left the U.S. Navy base in Cuba on Saturday afternoon, a senior Defense official told CNN. The United States has "appropriate assurances" that Qatar will be able to secure the detainees there, where they are under a travel ban for a year.
The Afghan Taliban issued a statement on its website in Arabic and Pashtun announcing with "great happiness and joy" the exchange of Bergdahl for five of its imprisoned senior leaders.
Bergdahl's parents issued a statement thanking the Emir of Qatar, the U.S. government and the former captive's supporters.
"We were so joyful and relieved when President Obama called us today to give us the news that Bowe is finally coming home! We cannot wait to wrap our arms around our only son."
The operation was so secretive that Afghan President Hamid Karzai was left out of the loop.
"Secretary (of State John) Kerry did inform President Karzai after the fact," Hagel said. "We couldn't afford any leaks anywhere for obvious reasons."
The journey home
Bergdahl was first transferred to Bagram Airfield, the main U.S. base in Afghanistan, for initial medical evaluation, before boarding a plane for Landstuhl, the largest American hospital outside the United States.
With more than 110 physicians and 250 nurses, the hospital has been the primary treatment center for soldiers hurt during Operations Desert Shield and Storm and Operation Enduring Freedom in Afghanistan and Operation Iraqi Freedom, the Army website said.
The hospital has also treated nonmilitary personnel, such as hundreds of Bosnian refugees injured in a 1994 bombing and Americans and Kenyans hurt in the 1998 bombing of the U.S. Embassy in Nairobi. In 2006, ABC news anchor Bob Woodruff and cameraman Doug Vogt were taken the Landstuhl hospital after being wounded by a bomb in Iraq.
Held by warlord
Bergdahl was deployed to Afghanistan in May 2009. He was 23 at the time of his capture, which happened after he finished a guard shift at a combat outpost on June 30, 2009, in Paktika province.
He was believed to be held by operatives from the Haqqani network, an insurgent force led by warlord Siraj Haqqani, who has a reputation for holding positions that are extreme even by Taliban standards.
The network is affiliated with the Taliban and al Qaeda, and it was not always clear whether Haqqani operatives would abide by any agreement among the United States, Qatar and the Taliban.
An Afghan Taliban commander not authorized to speak to the media confirmed to CNN that Bergdahl was captured by insurgents with links to the Haqqani network in Pakistan. Over the years, the captive was transferred back and forth between Afghanistan and Pakistan.
Hagel said Bergdahl's release made him think of his own time as a POW during the Vietnam conflict.
"There is some emotion for me in this because of my own experiences and the people that I know, (Sen.) John McCain and others who have endured many, many years of being separated and held in solitary confinement," he said.
Hagel said he hoped to speak personally with Bergdahl.
"When the doctors say that it's appropriate that I can speak with him I will do that," he said. "We just got him on the plane."
Critics question the negotiations
The United States has long declared that it won't negotiate with groups linked to terrorists, but analysts have said the United States has effectively maneuvered around the edges of that declaration over the years.
"As the administration has repeatedly affirmed, we will not transfer any detainee from Guantanamo unless the threat the detainee may pose to the United States can be sufficiently mitigated and only when consistent with our humane treatment policy," a senior administration official told CNN, adding that the detainees will be "subject to restrictions on their movement and activities."
Many of the released Guantanamo detainees held political positions in the Taliban government that fell in Operation Enduring Freedom in 2001.
But McCain, a former POW, called the released detainees "hardened terrorists who have the blood of Americans and countless Afghans on their hands." He demanded to know exactly what steps are being taken to guarantee that they never fight against the United States again.