BOSTON (Reuters) - Disaffected people living in the United States may develop radical ideologies and potentially violent skills over the Internet and that could present the next major U.S. security threat, U.S. "We now have a capability of someone to radicalize themselves over the Internet," Chertoff said on the sidelines of a meeting of International Association of the Chiefs of Police. "They can train themselves over the Internet. They never have to necessarily go to the training camp or speak with anybody else and that diffusion of a combination of hatred and technical skills in things like bomb-making is a dangerous combination," Chertoff said. "Those are the kind of terrorists that we may not be able to detect with spies and satellites." Chertoff pointed to the July 7, 2005 attacks on London's transit system, which killed 56 people, as an example a home-grown threat. To help gather intelligence on possible home-grown attackers, Chertoff said Homeland Security would deploy 20 field agents this fiscal year into "intelligence fusion centers," where they would work with local police agencies. By the end of the next fiscal year, he said the department aims to up that to 35 staffers.