(CNN) - In the dark of night, U.S. helicopters approached a high-walled compound in Pakistan on a mission to capture or kill one of the world's most notorious terrorist leaders.

Less than 40 minutes later - early Monday morning in Pakistan - Osama bin Laden was dead, along with four others inside the complex, and the U.S. forces departed with the slain al Qaeda leader's body to fulfill a vow that originated shortly after the September 11, 2001, terrorist attacks on the United States.

And as he announced the raid at the White House Sunday night, U.S. President Barack Obama called bin Laden's death "the most significant achievement to date in our nation's effort to defeat al Qaeda."

Obama, top officials watch raid unfold in real time

One senior administration official called the investigation a "team effort" and a "model of really seamless cooperation" across agencies.

This official and others briefed reporters on further details about the assault on the compound, which they believe was built five years ago for the specific purpose of hiding bin Laden - known by the code name "Geronimo," a U.S. official said.

The compound is in Abbottabad, about 50 kilometers (31 miles) north of the Pakistani capital of Islamabad. The city sits in a mountainous region that is not heavily populated. Many of the residents are army personnel.

While senior administration officials would not offer a breakdown of the U.S. mission's composition, a senior defense official said U.S. Navy SEALs were involved.

After years of intelligence work and months of following a specific lead, they traced a courier linked to bin Laden to the compound in Abbottabad, the officials said.

(CNN) - Osama bin Laden's death marked the end of an era for U.S. investigators, who searched remote villages and mountain caves in a far-reaching manhunt for the al Qaeda leader.

Their search, which lasted more than a decade, ended early Monday in Pakistan (Sunday night in the U.S.), when a small U.S. team raided a heavily guarded hideout in Pakistan and killed him.

The key break in the case came in August, when senior Obama administration officials say U.S. intelligence homed in on a $1 million compound in an affluent area north of Islamabad where one of bin Laden's couriers lived.

But the trail that eventually led the United States to bin Laden began years ago, the officials said.

After years of thwarted searches and dead ends, finding the elusive bin Laden had become "America's most vexing intelligence problem," one senior Obama administration official told reporters in a background briefing in Washington early Monday.

A new lead emerged when post-9/11 detainees gave investigators a glimpse into the al Qaeda chief's inner circle, the official said. During questioning, detainees repeatedly mentioned the nickname of a man they said was one of the few couriers bin Laden trusted.

That was the beginning of what President Barack Obama's top counterterrorism adviser described as a painstaking process.

Editor's note: Since becoming CNN's State Department producer in 2000, Elise Labott has covered four secretaries of state and reported from more than 50 countries. Before joining CNN, she covered the United Nations. Follow her on Twitter at @eliselabottcnn.

Washington (CNN) - The death of Osama bin Laden could prove to be a turning point in United States-Pakistani counterterrorism cooperation. But whether it is for better or for worse remains to be seen.

Ties between the two countries were at their lowest point in years before Sunday's attack on the compound where bin Laden was believed to be hiding for close to a year.

Until recently, Pakistan offered tacit support for U.S. drone strikes in its tribal areas targeting al Qaeda and Taliban leaders. But the drone campaign, which was intensely unpopular among the Pakistani public, had increasingly become one of the main irritants in the relationship between the two countries.

Islamabad was still seething over a January incident in which CIA contractor Raymond Davis shot and killed two Pakistan men who he claimed were trying to rob him.

For its part, the U.S. has been frustrated over what it calls Pakistan's lukewarm action in going against extremists. Two weeks ago, Adm. Michael Mullen, chairman of the U.S. Joint Chiefs of Staff, said while in Pakistan that links between elements of the Pakistan Inter-Services Intelligence agency, or ISI, and Taliban factions in Afghanistan that target U.S. troops were straining relations.

On bin Laden, President Obama said Pakistan helped provide intelligence that led the U.S. to the terrorist leader and praised Pakistan for its "close counterterrorism cooperation" but said no other country, including Pakistan, knew about the operation in advance.

Several Pakistani officials disputed Obama's account, claiming credit for what they called a joint U.S.-ISI operation.

A senior Pakistani intelligence official said the U.S. intelligence was developed from information that the Pakistanis had gathered: mostly electronic intercepts that the source said the Pakistanis regularly provide to the U.S.

"Somehow it slipped from our radar and was picked up on theirs," the official said.