President Bush is taking part in two days of somber events to mark the fifth anniversary of the September 11th, 2001, terrorist attacks in the United States.
He and first lady Laura Bush are to participate in a wreath-laying ceremony on Sunday at the site in New York City known as "ground zero," where the World Trade Center towers once stood.
Al-Qaida terrorists hijacked four commercial airliners on September 11th, 2001, and used two of them to take down the 110-story buildings.
Vice President Dick Cheney, speaking on NBC television, said the United States has done enormous damage to al-Qaida, and finding al-Qaida leader Osama bin Laden continues to be a top priority.
Secretary of State Condoleezza Rice told Fox News that the United States is safer and intelligence is much stronger since the attacks.
Monday, the president and first lady will take part in ceremonies at the sites where the two other hijacked airliners crashed -- a field near Shanksville, Pennsylvania, and at the Pentagon just outside Washington.
Nearly three-thousand people died in the attacks five years ago.