(WASHINGTON) -- FBI Director Robert Mueller issued a new warning Thursday about the threat of terror in the country, saying that dozens of sleeper agents -- al Qaeda operatives from Iraq -- may be living in the U.S.
Speaking before a House intelligence committee, Mueller said, "we are closely monitoring threats from al Qaeda in Iraq. Individuals who may have been resettled here in the United States that have had some association with al Qaeda in Iraq."
On Wednesday, Michael Leiter, director of the National Counterterrorism Center, also raised concerns about the same emerging threat.
"We are concerned that al Qaeda in Iraq remains committed to conducting external operations, to include the U.S. Homeland," said Leiter.
A senior law enforcement official told ABC News that intelligence developed in Iraq and a study of travel patterns from that country points to "dozens" of persons of interest in the United States. An intelligence source said investigations and surveillance of some individuals are now underway.
Mueller's concerns came a day after Homeland Security Secretary Janet Napolitano warned that this may be the most dangerous time since 9/11.
"In some ways, the threat today may be at its most heightened state since the attacks nearly 10 years ago," Napolitano said Wednesday.
Authorities point to threats from homegrown radicals fueled by the Internet and threats from Pakistan, Afghanistan and Yemen.
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