WASHINGTON, May 2: US Navy SEALs led the commando operation that ended the life of 9/11 mastermind Osama bin Laden with a bullet to the head.

The SEALs, which stands for Sea, Air, Land, are elite troops used for such missions. They were loaned to the CIA on Sunday night into Monday.

CIA Director Leon Panetta led the operation.

Two US helicopters swept into the compound at 1:30 and 2 am on Sunday morning.

Twenty to 25 US Navy Seals under the command of the Joint Special Operations Command in cooperation with the CIA stormed the compound and engaged Osama and his men in a firefight, killed Osama and all those with him.

Two Osama couriers were killed, as was one of Osama bin Laden’s son, and a woman reportedly used as a shield by one of the men. Other women and children were present in the compound but were not harmed. US officials said that Osama himself fired a weapon during the fight.

One of the US helicopters was damaged but not destroyed during the operation, and US forces elected to destroy it with explosives. US troops took Osama’s body into custody after the firefight and confirmed his identity.

The operation took shape after detainees in US custody identified a trusted Osama courier as someone who might have been living with and protecting the militant leader.

That courier became a key lead in locating Osama, the officials said.

Here is what senior US officials told journalists at a past-midnight briefing on Sunday/Monday at the White House.

Four years ago: Officials uncovered the courier’s identity.

Two years ago: Investigators identified areas of Pakistan where the courier and his brother lived.

August 2010: The residence of the courier and his brother was found in Abbottabad, President Barack Obama was informed.

September 2010: The CIA concluded that in fact Osama may be at the compound in Abbottabad.

February 2011: US officials concluded there was a “sound intelligence basis” for pursuing Osama at that location.

March and April 2011. President Barack Obama held a series of National Security Council meetings to develop courses ofaction to bring justice to Osama bin Laden.”

There were at least five NSC meetings — March 14, March 29, April 12, April 19, and April 28.

April 29, 2011: President Obama gave the final order to pursue the operation.

May 2, 2011: A US military team conducted a small helicopter raid on the compound. The team was in thecompound for 40 minutes.

It did not encounter any local authorities during the raid.

Osama resisted the assault force and died in a firefight. Along with Osama, three adult males were killed. Two were believed to be the couriers and one was a son of Osama.

A woman used as a human shield by a male combatant died and two women were injured.

A helicopter was lost because of mechanical failure. Intelligence on Osama was not shared with Pakistan and other countries.After the raid, US officials briefed President Asif Ali Zardari and other world leaders.

Osama has been buried at sea and his body was handled in the Islamic tradition. The officials did not elaborate.

When the compound was built in 2005, it was on the outskirts of the town centre, at the end of a narrow dirt road.

In the last six years, some residential homes have been built nearby.

The physical security measures of the compound are extraordinary. It has 12- to 18-foot walls topped with barbed wire.

Internal wall sections — internal walls sectioned off different portions of the compound to provide extra privacy.

Access to the compound is restricted by two security gates, and the residents of the compound burn their trash, unlike their neighbours, who put the trash out for collection.

The main structure, a three-storey building, has few windows facing the outside of the compound. A terrace on the third floor has a seven-foot wall privacy — has a seven-foot privacy wall.

It’s also noteworthy that the property is valued at approximately $1 million but has no telephone or Internet service connected to it. The brothers had no explainable source of wealth. US intelligence analysts concluded that this compound was custom built to hide someone of significance.

They learned that more people were living at the compound than the two brothers and their families. A third family lived there — one whose size and whose make-up matched the Osama family members that USofficials believed most likely to be with Osama bin Laden.

US officials, based on a large body of reporting from multiple sources, believed that Osama was living there with several family members, including his youngest wife.

Everything they saw — the extremely elaborate operational security, the brothers’ background and their behaviour, and the location and the design of the compound itself was perfectly consistent with what US experts expected Osama’s hideout to look like.

US officials kept in mind that two of Osama’s gatekeepers, Khalid Sheikh Mohammed and Abu Faraj al-Libbi, were arrested in the settled areas of Pakistan.

US analysts looked at this from every angle, considering carefully who other than Osama could be at the compound.

They conducted red team exercises and other forms of alternative analysis to check their work. “No other candidate fit the bill as well as Osama did.”

So the final conclusion, from an intelligence standpoint, was two-fold. “We had high confidence that a high-value target was being harboured by the brothers on the compound, and we assessed that there was a strong probability that that person was Osama bin Laden.”