Soon after the September 11 terrorist attacks, officials at the Pentagon's Defense Advanced Research Projects Agency began worrying that the next attack against the United States might involve the kind of deadly suicide bombings of malls, restaurants, or theaters that have been so widespread in Israel. So DARPA began a quiet collaboration with the Israeli government to use that country's vast video databases of suicide bombers approaching targets to develop biometric face and gait recognition software, sensors, radar, and other technologies to detect and deter suicide bombers, a former military official familiar with the program told U.S. News.

In fact, since 9/11, hundreds of U.S. bomb technicians, police chiefs, police officers, and FBI, Secret Service, and Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) agents have made repeated trips to Israel to learn from their counterparts and their extensive experience in detecting and deterring Palestinian suicide bombers. The train bombings in Madrid and London during the past two years and the U.S. military's daily bombardment from Iraqi insurgents' homemade bombs have only heightened the sense of urgency. Last month's arrests in Toronto and Paris of dozens of young Islamic men for allegedly plotting bombing attacks have raised the worry meter still further. Just a few days ago, FBI agents broke up what they described as a homegrown terrorist cell in Miami, arresting seven people for allegedly plotting attacks on the Sears Tower in Chicago and the FBI and other federal buildings in Miami.

In a speech delivered before the City Club of Cleveland a day after the arrests, FBI Director Robert Mueller said that pockets of "self-radicalized" jihadists represent the new face of global terrorism. "These extremists are self-recruited, self-trained, and self-executing," said Mueller. "They answer not to a particular leader but to an ideology. In short, they operate under the radar. And that makes their detection that much more difficult."

Since last fall, the U.S. government has made it a top priority to understand what factors triggered this self-radicalization, especially among second- and third-generation Muslim youth in England, Spain, the Netherlands, and Canada, U.S. Newshas learned. "Understanding radicalism," says a senior U.S. intelligence official, "has become a high, high concern from the White House on down." In the coming months, the FBI, the Department of Homeland Security, and the National Counterterrorism Center will issue independent reports on radicalization abroad and its implications at home. "We are not going to wait till we get hit," the official said. "We want to understand it now so we can try to prevent it."

"It's coming." According to a nonpartisan survey released in June of more than 100 top foreign-policy experts, the most likely form of attack on American soil is a suicide bombing--far more likely, they said, than a chemical or biological attack, an attack on a nuclear power plant, or a so-called dirty (radiological) bomb; 67 percent said that the next big attack on American soil, though perhaps years away, is likely to be a suicide bombing. "It's coming. You know it's coming," says James Cavanaugh, a senior ATF official and top explosives expert who just returned from Israel. "Al Qaeda has made suicide terrorism the binding force of the jihad movement."