They had trained tirelessly and prepared for every conceivable contingency — guards armed with automatic weapons, martyrs with suicide bombs lashed to their bodies, escape routes through which the most wanted man in the world might yet elude them — except for the one that greeted them when they reached the third floor of the compound in Abbottabad and headed for an open door, weapons poised.

A white flag hung from the door. Inside the room, standing against the far wall, her hands raised, was a young woman. Next to her, with his hands raised, stood a 6-and-a-half foot tallman, clad in white robes, a small smile on his face. He spoke a single, brief phrase in Arabic.

“What did he say?” one SEAL shouted to the lone interpreter.

“He said— the interpreter shook his head in disbelief — “‘I surrender.’ ”

Seven thousand miles away, the men and women in charge of U.S. national security listened as the CIA director relayed the news from the SEAL team. After years of effort, months of planning, hours of anxiety, there was a long moment of silence.

“We can’t let the S.O.B. live!” the vice president said. “Leon, he’s a lawful target, right?”

The CIA chief shook his head. “They had full authority to kill him,” he explained. “But under the rules of engagement, if he in fact threw up his hands, surrendered and didn’t appear to represent any kind of threat, then they were to capture him. And if the video showed our guys shooting a man in the obvious act of surrendering . . .” He stopped as the image of the terrorist leader appeared on-screen.

“You know what really gets to me?” the president said. “That smile. Almost like he knows something we don’t.”

By the time 2011 came to an end, they had a much better idea of what Osama bin Laden had been smiling about.

It all began with a triumph. On Sunday evening, May 1, President Obama strode down a red carpet and spoke to the nation from the East Room of the White House: “Good evening. Tonight, I can report to the American people and to the world that the United States has conducted an operation that captured Osama bin Laden, the leader of al-Qaeda, and a terrorist who’s responsible for the murder of thousands of innocent men, women, and children. It is the unbreakable intention of this country to bring him to justice.”

But by morning, the chants of “U.S.A.! U.S.A.!” in city streets, on college campuses, outside the White House, even at a nationally televised baseball game had given way to questions.

“Why did we take him alive?” a dozen radio talk-show hosts asked. “Aren’t 3,000 dead Americans enough?”

“I am sure,” Rush Limbaugh thundered, “that Attorney General Holder is prepared to bring charges against those SEALs that they didn’t read Osama his Miranda rights.”

Among congressional Republicans, praise for the capture was followed by demands for swift justice — including a suggestion by one House member that bin Laden be executed and buried in pigskin “to prevent him from meeting up with those 72 virgins in paradise.”

But U.S. officials faced a far more consequential challenge: Where would bin Laden go, and what would happen to him? The arguments began almost as soon as the terrorist leader arrived at Bagram air basehigh in the mountains of Parwan province in Afghanistan.

Put him on trial for mass murder in a New York federal court? Nearly 3,000had died there. But what if information about his location had been obtained through “enhanced interrogation techniques” and was ruled inadmissible? What if bin Laden acted as his own lawyer, turning the trial into a months-long denunciation of America? What if one holdout resulted in a hung jury?

And anyway, the furious reaction to previous efforts to try Khalid Sheik Mohammed in Manhattan — local politicians reversing themselves, Congress denying funds for such a trial — made that idea impossible.

What about an international tribunal, to drive home the fact that bin Laden’s crimes were against humanity?

“As a political matter,” one White House insider reflected anonymously to the press, “that would have brought the wrath of the right down on us: ‘We were the ones he attacked, and we’re going to be the ones to deal with him.’ ”

“Besides,” she added, “the International Criminal Court could deal only with crimes committed after 2002. As for a war crimes tribunal at The Hague, that court would not impose the death penalty — can you imagine the president signing off on that small detail?”

A military commission at Guantanamo Bay, then? The process was agonizingly slow (only five cases concluded in nine years), and a death sentence for bin Laden would mean years of appeals.

Even the legal questions were nothing next to the security consequences of taking bin Laden alive.

His survival enhanced his image as an outlaw-hero who had outwitted the West. When an anonymous solider or worker at Bagram snapped a cellphone picture of Osama, smiling and flashing a V sign, the image appeared on Web sites around the world and on posters in dozens of cities, with supporters chanting: “The sheik lives!”

And early on the morning of Dec. 22, members of Lashkar-i-Taiba, the Pakistan-based terror organization responsible for the Mumbai slaughters of 2008, seized an elementary school in New Delhi, holding more than 200 children and teachers hostage and threatening to kill them unless bin Laden was released within 72 hours. Simultaneously, a dozen terrorists attacked the U.S. Embassy in Islamabad, killing three guards before being repulsed.

Within the administration, suspicion arose that Pakistan’s Inter-Services Intelligence agency was linked to these attacks. The ISI, long believed to have ties to the Taliban, had been enraged at Washington for violating Pakistani sovereignty in the bin Laden raid. Those suspicions further eroded U.S. relations with a nation long considered indispensable to the Afghan war effort.

The attacks also stirred fears of similar acts aimed at U.S. Embassies, bases and businesses around the globe. Back home, airport security was heightened so much that holiday travelers faced four-hour screening delays, countless missed flights and jangled nerves.

On Christmas Eve, the president — forced by political pressure to cancel his own Hawaii vacation — gathered his inner circle in the Oval Office for a cheerless Christmas toast. “Any wishes for the holidays?” someone asked.

“Yes, actually,” Obama said. “I wish someone had pushed that bastard out of the helicopter seven months ago.”

Jeff Greenfield, a former network correspondent for ABC, CNN and CBS, is the author of “Then Everything Changed: Stunning Alternate Histories of American Politics: JFK, RFK, Carter, Ford, Reagan.”

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