WASHINGTON -- The nail-biting, 40-minute clandestine operation that resulted in Osama bin Laden's death could have been a calamitous political and military failure; a bloodbath in Pakistan that left U.S. forces and scores of civilians dead or captured by America's most ferocious enemy.
Or, as it happened, it could unfold largely in textbook fashion - delivering a stunning success for the often maligned intelligence community, a political and national security coup for a struggling president and revenge for Americans still carrying vivid memories of Sept. 11.
By secretly sending a team of special operations forces into an enemy fortress in a suburban neighborhood of a sovereign country, President Barack Obama chose the path of greatest risk, but also greatest reward.
There were so many ways it could have gone wrong.
As U.S. officials evaluated their options, Obama asked for a gut check from top members of his national security team.
The various plans, White House counterterror chief John Brennan said, were "debated across the board and the president wanted to make sure, at the end, that he had the views of all."
The level of risk stretched from moderate to massive.
"When you go into something like this, there are no guarantees," said Dick Couch, a Navy SEAL during the Vietnam War who later worked for the CIA. "There's the fog of war. Things go wrong that you don't really plan or intend."
Bin Laden might not have been there, the commandos could have run into stiff resistance or hidden explosives, or U.S. troops might have been detected by Pakistani forces who could have taken action against them, Couch said in a phone interview Tuesday. "They have to plan ahead and account for as many of these contingencies as possible," he added. "But you can't take all the risk out of it."
An airstrike, like the one that killed al-Qaida in Iraq leader Abu Musab al-Zarqawi in an Iraq safe house in June 2006, could be done quickly, from a drone or bomber far away, generating little risk for U.S. troops. In that operation, U.S. special operations forces went in after the F-16 strike and collected documents, electronic storage devices and weapons that were hidden under the floorboards in the building.
But that safe house was in a war zone where U.S. forces where already engaged.
Still, a bombing brings its own shortcomings: a misfire, an aircraft problem, the potential for widespread civilian casualties and difficulty in identifying enemy remains.
Putting troops on the ground in Pakistan was by far the most dangerous option, both militarily and politically.
While an ally, Pakistan is a sovereign nation that has complained bitterly about U.S. drone strikes targeting insurgents within its borders. And Islamabad officials have strongly resisted having U.S. combat troops on Pakistani soil.
Obama knew that anything short of a clean and victorious mission would have dire consequences, further eroding an already tenuous relationship with Pakistan during a critical period of the Afghanistan war. The U.S. needs Pakistan's assistance rooting out terrorists along the border and helping to prevent militants from crossing into Afghanistan as they become more active in the warmer spring weather.
At the same time, a helicopter assault that dropped elite commandos into the bin Laden compound forced them into direct combat, putting American lives in greater danger and presenting a greater risk of aircraft or equipment failures.
It also required exhaustive planning and training, which provided greater chances for information to leak out over the ensuing months, scuttling the mission and sending bin Laden deeper into hiding.
The benefits, however, were too rich to ignore. With a precision assault, there would be much greater certainty they would positively identify bin Laden - a linchpin for success. It also reduced the risk of mass civilian casualties and dramatically increased the opportunity to gather what officials call a treasure trove of documents and intelligence.
As he reviewed the options, Obama had history to consider. As some of his predecessors can attest, these are the missions that can define a presidency.
President Jimmy Carter's failed re-election bid was blamed in part on the disastrous attempt to rescue American hostages from the U.S. Embassy in Tehran in 1980. Eight American troops were killed when a special operations aircraft collided with a Navy helicopter at a rendezvous point in the desert on their way to the embassy.
And in the 1993 Battle of Mogadishu, made famous in the movie "Black Hawk Down," two helicopters were shot down and 18 American soldiers were killed during a U.S. mission to snatch a Somali clan warlord. The same kind of helicopters were used in the bin Laden raid.
The images of gunmen dragging the bodies of U.S. soldiers through Mogadishu's dusty streets became an icon for those opposed to U.S. involvement overseas. President Bill Clinton ordered a U.S. withdrawal and promised to never again deploy troops unless there was a clear U.S. national interest.