WASHINGTON – Deputy National Security Adviser for Homeland Security and Counterterrorism, and Assistant to the US President John Brennan said that Osama bin Laden was involved in a firefight with US forces when he was killed on Sunday in Pakistan.Brennan on Monday said that minimizing the risk to American operatives and the surrounding civilian population informed the decision about which of several different approaches to take against the compound believed to hold bin Laden.Obama: "Justice has been done"Earlier Monday, Obama proclaimed “This is a good day for America" as the country and much of the world celebrated the death of the man behind the deadliest terror attack on American soil, a day after US Navy SEALs took out bin Laden in a covert helicopter raid in Pakistan.Leaders across the globe congratulated the US, including Prime Minister Binyamin Netanyahu, who released a video Monday praising America’s president and military on their operational triumph.“It took 10 years to track Osama bin Laden down. It took 10 years to bring a measure of justice to his victims. But the battle against terror is long and relentless and resolute,” he said. “This is a day of victory, victory for justice, for freedom and for our common civilization.”Bin Laden was killed in a carefully planned helicopter raid that was kept secret even from the Pakistani government. US officials revealed that the al-Qaida leader, who masterminded the 9/11 attacks and taunted the US repeatedly in video and audio messages issued over the past decade, used his wife as a human shield during the gun-battle that took his life. After bin Laden’s identity was confirmed, his body was thrown into the ocean.“Our country has kept its commitment to see that justice is done,” Obama told families of war veterans receiving the Medal of Honor at the White House. “The world is safer. It is a better place because of the death of Osama bin Laden.”But American officials warned that the fight against al-Qaida and the other extremist groups that threaten America is far from over.“The fight continues and we will never waver,” Secretary of State Hillary Clinton declared at the State Department Monday morning. “We must take this opportunity to renew our resolve and redouble our efforts.”In particular, she stressed, “In Afghanistan we will continue taking the fight to al-Qaida and their Taliban allies.”In the short term, top US officials were also warning that the country, and particularly Americans abroad, should brace for retaliatory strikes.CIA Director Leon Panetta said al- Qaida would “almost certainly” try to avenge the killing of Osama bin Laden.“Though bin Laden is dead, al-Qaida is not. The terrorists almost certainly will attempt to avenge him, and we must – and will – remain vigilant and resolute,” Panetta said.The State Department sent out an unusual worldwide travel warning for American citizens in anticipation that there could be revenge attacks, though the Department of Homeland Security said it had no information of specific threats to upgrade its alert system.On the local level, however, security personnel were stationed outside sensitive sites, including synagogues.Reuters contributed to this report.He said that a small-team helicopter raid was chosen also because it would gave the US the best chance at being able to verify that they had taken bin Laden and to minimize friction with the Pakistani government, which was not informed of the raid before it occurred.Brennan said that while the US had a high degree of confidence that bin Laden was inside the compound – a million-dollar, high-walled, one-of-its-kind estate lacking Internet and phone connectivity in the affluent town of Abbottabad, some 35 miles north of Islamabad – there was no confirmation before the early morning operation that bin Laden was inside.Brennan said US President Barack Obama’s decision to go ahead with the raid, despite lacking unanimity among his advisors, was one of the “gutsiest calls of any president in recent memory.”He said that the US is now “99.9 percent” certain that the US commandos had killed bin Laden, given DNA, appearance and other telling information, but demurred on whether the government would release photos as many have demanded.The order was given to take bin Laden alive if possible, but if encountering likely resistance, he could be killed on sight, according to Brennan. He said bin Laden was killed in the firefight, along with his son, two couriers at the house and his wife, the latter of whom appeared to have been used as a human shield.Bin Laden’s body was thrown into the ocean so it will not become a shrine for terrorists, Brennan said.In addition to whether to release the photo of bin Laden, who apparently died of gunshot wound to the head, the elimination of al-Qaida’s top leader has triggered a number of policy debates. Chief among them are how to deal with Islamabad – which US officials repeatedly called a “partner” and active in counter-terror work despite serious questions about how bin Laden could have lived in such an unusual, urban compound without the knowledge of at least some Pakistani officials.Critics of the war in Afghanistan are also suggesting that the fight there can now wind down more quickly since its chief objective has been met.But Brennan said the purpose of the fighting in Afghanistan was to make sure al-Qaida could never again operate out of the mountainous country, and US Senator Joe Lieberman, an Independent from Connecticut who heads the Homeland Security Committee, said it would be a mistake to back off now.“The killing of bin Laden gives us increased momentum in the war in Afghanistan,” he said. “If I were a leader of the Taliban, if I were Mullah Omar, I’d be frightened right now.”He added that the US had to seize the opportunity presented by this moment in history to support the emergence in democracy in the Middle East.“To rid our world not only bin Laden but bin Ladenism, it is critical that we do everything we can to help the democratic forces in the Middle East succeed,” he said. “For it will be at the hands of his fellow Arabs and his fellow Muslims that bin Laden is finally and firmly consigned to the trash heap of history.”Regarding the replacement of extremism with democracy, Clinton said, “There is no better rebuke to al-Qaida and its heinous ideology.”Brennan assessed that eliminating bin Laden struck a major blow against al-Qaida and its appeal to terrorist groups across the world, as it cut off the head of the snake.“This is a strategic blow to al-Qaida,” he said.But other terrorism and foreign policy experts disagree with how significant this development will be to the global fight against extremism.“As welcome as this is, I don’t think it transforms the nature of the threat or the challenge that we face,” Richard Haass of the Council on Foreign Relations warned. “We were successful in this case in killing Osama bin Laden, but this disease and the scourge of terrorism remains. We have to be prepared for the long haul.