WASHINGTON -- The Pentagon concluded in 2010 that Army Sgt. Bowe Bergdahl walked away from his unit, and after an initial flurry of searching the military curbed any high-risk rescue plans. But the U.S. kept pursuing avenues to negotiate his release, recently seeking to fracture the Taliban network by making its leaders fear a faster deal with underlings could prevent the freedom they sought for five of their top officials, American officials told The Associated Press.

The U.S. government kept tabs on Bergdahl's whereabouts with spies, drones and satellites, even as it pursued off-and-on negotiations to get him back over the five years of captivity that ended on Saturday.

Bergdahl was in stable condition Monday at a U.S. military hospital in Germany, but questions mounted at home over the way his freedom was secured: Five high-level members of the Taliban were released from the U.S. prison in Guantanamo Bay, Cuba, and sent to Qatar. The five, who will have to stay in Qatar for a year before going back to Afghanistan, include former ministers in the Taliban government, commanders and one man who had direct ties to the late al-Qaida chief Osama bin Laden.

A U.S. defence official familiar with efforts to free Bergdahl said the U.S. government had been working in recent months to split the Taliban network. Different U.S. agencies had floated several offers to the militants, and the Taliban leadership feared that underlings might cut a quick deal while they were working to free the five detainees at Guantanamo, said the official and a congressional aide, both of whom spoke only on condition of anonymity because they were not authorized to speak publicly about efforts to release Bergdahl.

There was plenty of criticism about how the deal came about.

"Knowing that various lines of effort were presented and still under consideration, none of which involved a disproportionate prisoner exchange, I am concerned by the sudden urgency behind the prisoner swap, given other lines of effort," said Rep. Duncan Hunter, who has criticized the government effort to seek Bergdahl's release as disorganized.

One current and one former U.S. official said Obama had signed off on a possible prisoner swap. The president spoke to the Qatari emir last Tuesday, and they gave each other assurances about the proposed transfers, said a senior administration official, speaking on condition of anonymity because the official wasn't authorized to discuss the deliberations in public.

One official briefed on the intelligence said the Taliban also may have been worried about Bergdahl's health, having been warned that the U.S. would react fiercely if he died in captivity. The Landstuhl Regional Medical Center in Germany, which is caring for Bergdahl, said he was suffering from nutritional issues.

Bergdahl's handoff to U.S. special forces in eastern Afghanistan was never going to lead to an uncomplicated yellow-ribbon celebration. The exchange stirred debate over a possibly heightened risk other Americans being snatched as bargaining chips and whether the released detainees would find their way back to the battlefield.

Republicans in Congress criticized the agreement and complained about not having been consulted, citing a law that requires Congress to be given 30 days notice before a prisoner is released from Guantanamo.

Republicans on the House Armed Services Committee said the Pentagon notified the panel by phone on Saturday that the exchange was occurring in the next five hours.

"A phone call does not meet the legal standard of congressional notification," the Republican members said in a statement and added that official notice of the move came Monday, "more than 72 hours after the detainees were released."

Republicans also argued that the swap could set a dangerous precedent.

"The five terrorists released were the hardest of the hard-core," said Sen. Lindsey Graham. "I fear President Obama's decision will inevitably lead to more Americans being kidnapped and held hostage throughout the world."

White House chief of staff Denis McDonough pushed back.

"All Americans should know that we did what was necessary to get Bowe back," he said in a speech to a think-tank . "We did not have 30 days to wait to get this done. And when you're commander in chief, you have to act when there is an opportunity for action."

U.S. officials said they had to act quickly because Bergdahl's health and safety appeared in jeopardy, but declined to explain how.

Bergdahl disappeared on June 30, 2009. A Pentagon investigation concluded in 2010 that the evidence was "incontrovertible" that he walked away from his unit, said a former Pentagon official who has read it.

The military investigation was broader than a criminal inquiry, this official said, and it didn't formally accuse Bergdahl of desertion. In interviews as part of the probe, members of his unit portrayed him as a naive, "delusional" person who thought he could help the Afghan people by leaving his army post, said the official, who was present for the interviews.

That official, like others cited in this report, spoke only on condition of anonymity because he was not authorized to comment publicly by name.

Nabi Jan Mhullhakhil, the provincial police chief of Paktika province in Afghanistan, where Bergdahl was stationed with his unit, said elders in the area told him that Bergdahl "came out from the U.S. base ... without a gun and was outside the base when he was arrested by the Taliban."

After weeks of intensive searching, the military decided against making an extraordinary effort to rescue him, especially after it became clear he was being held in Pakistan under the supervision of the Haqqani network, a Taliban ally with links to Pakistani's intelligence service.

Nonetheless, individual units pursued leads as they came in. The Pentagon official familiar with the talks said, "I know for a fact that we lost soldiers looking for him."

But the Pentagon maintained the circumstances of his capture were irrelevant.

"He is an American soldier," Rear Adm. John Kirby said. "It doesn't matter how he was taken captive. It doesn't matter under what circumstances he left. ... We have an obligation to recover all of those who are missing in action."

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Associated Press writers Richard Lardner, Donna Cassata and Robert Burns in Washington, Amir Shah in Kabul, Lolita C. Baldor in Brussels and Patrick Quinn in Cairo contributed to this report.