Brennan, who has spent 15 years trying to hunt down the notorious fugitive, reveled in the successful mission, which he described as "decapitating the head of the snake known as al-Qaeda" and severely weakening an already diminished organization.
"Here is Osama, living in a million-dollar compound, hiding behind women who were put in front of him as a shield," Brennan said. "It speaks to just how false his narrative has been over the years...he's putting other people out there" to wage jihad while he is secure in his luxury compound.
The President himself deserves enormous credit for giving the final green light to the nighttime raid, Brennan said, calling the decision one of the "gutsiest calls of any president in recent history."
There was an increasing confidence within the CIA that the bin Laden was living in the compound, but up until the last minute, U.S. officials could not be 100 percent certain, and there were members of the President's national security team who disagreed with the decision to order the raid, Brennan said.
"There was nothing to confirm that bin Laden was at the compound - the President had to evaluate the situation," Brennan said.
Bin Laden engaged in the firefight, but it was unclear if he picked up a firearm or shot any rounds. Brennan also identified bin Laden as the combatant who had used a woman as a human shield. She was the only woman who died in the operation, which also killed a courier for bin Laden, the courier's brother, and one of bin Laden's sons, Brennan said. Brennan later said it was his understanding that the woman was one of bin Laden's wives, but officials later said Brennan was mistaken -- his wife had only been injured in the attack.
"She served as a shield -- this is my understanding -- when she fought back -- when there was an opportunity to get to bin Laden -- she was positioned in a way that she was used as a shield," Brennan told reporters.
Brennan was repeatedly asked if the Navy Seals team that conducted the operations was under orders to kill, not capture, bin Laden.
"If we had the opportunity to take him alive, we would have done that," Brennan said, noting that he and other security officials expected bin Laden to fight back, which he did. "We're hoping to bury the rest of al-Qaeda along with bin Laden."
One of the most harrowing moments was when the helicopter carrying the seals encountered a mechanical failure. The Seal team had to destroy it and continue with their mission even though they had no way of knowing how they would escape the compound.
The U.S. did not inform the Pakistani government about the raid until after it had occurred and toward the end of the mission, the Pakistanis had begun scrambling their aircraft to respond to the unknown attack on the compound and the Seals did not know whether they would take fire or not. The special operations team managed to escape without injury.
Reporters peppered Brennan with questions about the decision to bury bin Laden at sea. Brennan said the decision was made in strict accordance with Islamic law before the raid as a contingency plan should they kill bin Laden. Islamic law requires Muslims to be buried within 24 hours of their death, and Brennan said ferrying bin Laden out of the country and securing an agreement of another country to bring him in and bury him would have exceeded that 24-hour period.
He would not say, however, exactly where and when the burial at sea occurred.
"It was looked at from the standpoint, if we captured or killed him what would we do?" Brennan said. "It was determined that in the best interests of everyone involved that he be buried at sea within 24 hours."
Obama's national security team is still trying to determine whether to release photos of bin Laden's body and other details of the raid.
Brennan confirmed that the U.S. had not received specific threats in the wake of the killing but warned that al Qeada could act like a "wounded tiger" and remain dangerous. Still, he said, the organization is a shadow of its former self as people all over the Middle East are rising up against oppressive governments that value violence over democracy and peaceful protests.
Some would-be terrorists, Brennan said, must be saying to themselves, "Osama bin Laden is dead... terrorism is bankrupt, al Qaeda and bin laden are old news. This is the time to move forward. Terrorism is not the wave of the future. It's the wave of the past."
Ayman al-Zawahiri is expected to replace bin Laden on the U.S. Most Wanted List, but Brennan downplayed Zawahiri's ability to take up where bin Laden left off.
"Zawahiri is not charismatic. He was not involved in the fight early on in Afghanistan," Brennan said. "I think you are going to see them eating themselves from within more and more."