President George W Bush has defended his policy of pre-emptive military action and said the United States must stay on the offensive to ensure that the American people are protected from harm. Addressing the corps of cadets at the US Military Academy on Tuesday, the president said that after the Sept 11, 2001, terrorist attacks, the US saw the urgency of staying a step ahead of our enemies, a policy reflected in what is known as the Bush Doctrine. Bush said terrorism continues to pose a serious challenge, as seen in the attacks last month in Mumbai, but that the terrorists have been weakened. "Al-Qaida's top two leaders remain at large, yet they are facing pressure so intense that the only way they can stay alive is to stay underground. The day will come - the day will come when they receive the justice they deserve," Bush said to loud applause. Determined to shape his legacy, Bush has spoken about his record on combatting AIDS, his policy on the Middle East and what he has accomplished as commander in chief. He talked about strengthening allies against terrorism and sharing intelligence. And he talked about the military and military strategy since he took office in January 2001. "With all the actions we've taken these past eight years, we've laid a solid foundation on which future presidents and future military leaders can build," Bush said. "America's military - America's military today is stronger, more agile and better prepared to confront threats to our people than it was eight years ago. In the years ahead, our nation must continue developing the capabilities to take the fight to our enemies across the world. We must stay on the offensive. We must be determined and we must be relentless to do our duty to protect the American people from harm," he added.