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."  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.  A senior administration official said later that "Geronimo" was code for the act of capturing or killing bin Laden, not the man himself.  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.  When first built, the compound was secluded and reachable by only a dirt road, the officials said. In recent years, more residences built up around it, but it remained by far the largest and most heavily secured property in the area, they said.  The mission ordered Friday by Obama found outer walls up to 18 feet tall topped with barbed wire, with two security gates and a series of internal walls that sectioned off different portions of the compound, the senior administration officials said. The main structure was a three-story building with few windows facing the outside of the compound, and a third-floor terrace had a 7-foot privacy wall, they said.
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 --