WASHINGTON — The head of the Department of Homeland Security indicated Sunday that U.S. agencies were investigating possible "sleeper" cells in the country, a concern heightened by Thursday's attacks in London.
Asked whether there were Al Qaeda cells in the United States, Homeland Security Secretary Michael Chertoff pointed to groups in Portland, Ore., northern Virginia and elsewhere convicted on terrorism-related charges.
"We've seen these cells," he said in an interview on CBS' "Face the Nation." "And we're continuing to conduct active investigations of other cells."
Chertoff's response appeared to go beyond remarks from other federal law enforcement officials in recent months.
FBI Director Robert S. Mueller III testified before Congress in February that he was "very concerned" about a lack of intelligence on networks of Al Qaeda operatives in the United States, but he stopped short of saying there were sleeper cells in the country.
Critics have said that most cases brought in the United States against alleged terrorist cells have been weak, with little evidence of plots against domestic targets. Chertoff acknowledged that criticism but said U.S. agencies had been aggressive in disrupting groups before they became operational.
"A sleeper cell can become operational in the blink of an eye," he told NBC's "Meet the Press." "We can't wait until the fuse is lit."