President Barack Obama gave the go-ahead for U.S. forces to raid a northern Pakistan housing compound based on "what was probably a 50-50 chance that Osama bin Laden was there," his national security adviser said. "It was a circumstantial case ... But what he had 100 percent confidence in was the ability of our special forces to execute the mission,"

some advocated for the commando raid while others advised against it, Donilon said, given there had been no clear-cut sightings of bin Laden by that point.

After a night's sleep, Obama told Donilon at 8:20 a.m. the next day to draft the order for the raid. By Sunday evening -- which was early Monday morning in Pakistan -- the 38-minute mission was over, the 25-strong U.S. team having flown out of the country along with bin Laden's dead body. Like other Obama administration officials, Donilon applauded the decision and its end result of knocking out the No. 1 man on the FBI's "Most Wanted Terorist" list. He called it "the single biggest achievement we've ever had" in the fight against al Qaeda.