US Navy SEALs, legendarily tough, secretive specialists, led the bold commando operation in Pakistan that took down the world's most wanted man: 9/11 mastermind Osama bin Laden, US officials said.
After an embarrassing failure at rescuing hostages from the US embassy in Tehran in 1980, US authorities sought to bring hard-learned lessons into play seven years later with the launch of the US Special Operations Command.
The elite, highly trained unit of 2,300 men marked a historic milestone with their elimination -- with a bullet to the head -- of the world's most sought fugitive almost a decade after the September 11 terror strikes on US targets.
According to a US official, Navy SEALs -- an acronym for sea, air and land -- led the assault force which likely involved forces from across the armed services' Navy, Army, Air Force and Marine ranks.
There is no doubt the force used Army helicopter pilots and members of the Air Force, said Dick Hoffmann, a Rand Corporation expert who spent 20 years in the unit (1987-2007), which he called a classic "capture-kill" operation.
The New York Times reported that 79 commandos and a dog took part in the raid.
Since the beginning of former US president George W. Bush's "war on terror," these capture-kills have become the SEALs forte, Hoffman told AFP in an interview.
The goal is to try to get the target alive so intelligence can be secured, if and when possible. But when the person is armed and a threat to the unit, "you know the guys would put a couple of bullets in his forehead," Hoffmann said.
Bin Laden was killed by US bullets while he was resisting, a senior US defense official said.
Historically experts in intelligence gathering and sea-based assaults or strikes on ships, the SEALs have elite counterparts in the Air Force (Delta Force) and the Army (Green Berets), on the leading edge of US military intelligence gathering.
"Their guys have been doing operations in Iraq, Afghanistan for the last nine years. So they have been getting real world experience, that keeps them ready," explained Hoffmann.
Yet why was it the SEALs in the landmark operation as opposed to another unit?
"The different assault teams rotate in theater of operations through Central Command periodically. They just happened to be assigned to that theater during this period of time when the target popped up," Hoffmann added.
The residence in Abbottabad would have been identified six months earlier for rehearsals to have been run, he said.
The National Journal reported that a mock bin Laden residence had been built out of sight at Baghram north of Kabul for training runs. The report could not immediately be confirmed.
An assault team usually would have about 30 members and their capture-kill work in Iraq and Afhanistan led to captures about 80 percent of the time, Hoffman said.
"But that relies on the element of surprise. When you go in with helicopters, it makes noise and often ends up with resistance and you have to kill him," he explained.
Chopper piloting was the special challenge here, he said.
"The most difficult aspect in this particular mission was not the assault itself but was flying into the target area because at the time they had to fly under radar," with the Pakistanis not having been alerted, Hoffman said.
For Andrew Exum, an analyst at the Center for a New American Security, and a retired Army officer who served in Afghanistan war: "the tactical risks on this type of raid are not the real challenges. The political risk I think is much bigger.
If something goes wrong, "it's a nightmare," Exum stressed. "If a helicopter with Delta operators or SEALs goes down in the Pakistani heartland, that is a huge, huge problem.
"And so, it really is one of these things where you can do it, but you've got one chance."