President Bush has strongly defended the US-led war on terror, casting it as a struggle between freedom and tyranny similar to World War II.
Bush is running for re-election as a war president
In a speech to new air force officers, he said they were fighting the same war as those who battled the Nazis.
The war on terror, he said, resembles "the great clashes of the last century" between democracy and totalitarianism.
Mr Bush was speaking at the Air Force Academy, ahead of ceremonies marking the 60th anniversary of D-Day.
He told graduating officers in Colorado Springs: "Each of you receiving a commission today in the United
States military will also carry the hopes of free people
Like the US involvement in World War II, he said the war on terror began with a surprise attack on the US.
"Like the murderous ideologies of the last century, the ideology of murderers reaches across borders," President Bush added.
The "enemies of freedom", he went on, mistakenly assumed that the US was "decadent" and would collapse.
"In those calls we hear echoes of other enemies in other times, the same swagger," he said.
The president insisted that al-Qaeda and its supporters would be defeated.
"We will accept nothing less than victory over the enemy," he said.
He told the new officers that the US would continue to strike terror groups around the world.
"The best way to protect America is to stay on the offensive."
Mr Bush highlighted the importance of the Middle East, and re-affirmed his policy of fostering democracy there.
"If that region is abandoned to terrorists and dictators, it will be a constant source of violence and alarm," he said.
"If that region grows in democracy and prosperity and hope, the terrorist movement will lose its sponsors, lose its recruits
and lose the festering grievances that keep terrorists in business."
In the long term, the president added, "we expect a higher standard of reform and democracy from our friends in the region."
Mr Bush also defended his administration's controversial record on Iraq.
He said that country was "more secure with Saddam Hussein in a prison cell".