"For the past eight years, I have had no higher honor than serving as the commander in chief of these brave patriots," Bush said in his weekly radio address.

Bush praised the valor of U.S. troops on Sept. 11, 2001, "in service members rushing into smoke-filled corridors to save their colleagues at the Pentagon, and in planes patrolling the skies above New York City and Washington D.C."

He also recalled that many Americans enlisted in the military after Sept. 11 and praised the armed forces for their work in Afghanistan and Iraq.

"We saw their valor in battle-tested warriors who signed up for a second, or third or fourth tour -- and made the troop surge in Iraq that I announced two years ago today one of the great successes in American military history," he said.

Bush credited U.S. forces with liberating more than 50 million people and making the United States safer.

"We owe a debt of gratitude to all of these patriots," he said. "Because of their devotion to service, many Americans live their lives without the fear and uncertainty that they felt in the days just after 9/11."

The president warned against complacency, saying America "faces sworn enemies intent on striking our nation and our people. And we must remain vigilant for as long as that threat remains."