President Bush is marking the fifth anniversary of the September 11, 2001, terrorist attacks with a pilgrimage to the three sites where Americans lost their lives. It is a day of reflection for the president and the nation.

Throughout this day, images will tell the story: faces of the families of the dead, the barren pit where New York's World Trade Center towers once stood, the flags flying in remembrance at the Pentagon and in a field in western Pennsylvania, where the last of four hijacked planes went down.

President Bush and wife, Laura, lay memorial wreath in pool of water at ground zero

The president has no plans to speak at any of the commemorative events, although he will share his personal thoughts with the nation in a speech at the end of the day. In a recorded interview broadcast on the morning of the anniversary, he offered a bit of a preview.

He reflected on his first look at the devastation in New York in the days immediately following the collapse of the World Trade Center towers, and the words he shouted into a bullhorn, while standing with exhausted rescue workers atop a pile of crumbled concrete and twisted metal.

"I can hear you! The rest of the world hears you! And the people who knocked these buildings down will hear all of us soon," he said.

Mr. Bush told NBC's Today Show that those words captured the emotions of the day.

"That was not a planned speech. It just came out," the president explained. "There was smoke, and there was haze. The emotions were unbelievable. There were tears in peoples' eyes, there was hugging, there was exhaustion, and there was anger."

The president said there was no way to envision at that time that, five years later, 150,000 U.S. troops would be fighting in Afghanistan and Iraq. But he said the determination needed to wage the war on terror was already evident.

"I knew that we were going to have to be a nation of resolve, and I knew that we were dealing with cold-blooded killers, the likes of which we hadn't seen in a long period of time," he said.

He said once again that, five years after the attacks, America is safer, but not yet safe. He said the only way to protect the nation from the terrorist threat is to "defeat an ideology of hate with an ideology of hope."