Peter and Oprah

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According to Peter, the fact that al-Qaida remains determined to inflict damage upon the United States does not necessarily mean that we will see a repeat of a 9/11-style attack. Instead, he says future attacks are likely to be smaller in scale. "In London, they killed 56 people. In Madrid, they killed 191 people. The group remains pretty virulent, and suddenly there's an ideological movement the group has sort of spawned that can attack us," Peter says.

Though we are more aware of the existence of terrorist threats, there are significant vulnerabilities in our national defense.

One uncovered plot in Modesto, California, illustrates the danger. "There's a group of guys who got radicalized in prison," Peter says. "Some alleged that they were planning to attack U.S. military bases. They had weapons, they had a plan, they were going to attack synagogues. This seems to me like a pretty serious domestic terrorist cell."

Peter's experience in covering terrorism has led him to past predictions. "I was extremely concerned in the summer of 2001 that an attack was going to happen," Peter says. "So much information was flooding in about their desire to attack us around the world." Because of that, he says, "I knew that it was bin Laden as soon as the second plane hit."