Foreign fighters "are a small component of the insurgency," and Syrian, Saudi, Egyptian, Jordanian and Iranian nationals make up the majority of foreign fighters, he said.
On terrorism, Goss, FBI Director Robert S. Mueller III and the acting deputy director of the Department of Homeland Security reiterated their belief that al Qaeda and other jihadist groups intend to strike the United States but offered no new information about the threat.
"It may be only a matter of time before al Qaeda or another group attempts to use chemical, biological, radiological and nuclear weapons," Goss said.
Tom Fingar, assistant secretary of state for intelligence and research, submitted a written statement that said: "We have seen no persuasive evidence that al-Qaida has obtained fissile material or ever has had a serious and sustained program to do so. At worst, the group possesses small amounts of radiological material that could be used to fabricate a radiological dispersion device," or dirty bomb.
Mueller, whose bureau has the lead in finding and apprehending terrorists in the United States, said his top concern is "the threat from covert operatives who may be inside the U.S." and said finding them is the FBI's top priority. But he said they have been unable to do so.
"I remain very concerned about what we are not seeing," Mueller said.
"Whether we are talking about a true sleeper operative who has been in place for years, waiting to be activated to conduct an attack, or a recently deployed operative that has entered the U.S. to facilitate or conduct an attack, we are continuously adapting our methods to reflect newly received intelligence and to ensure we are as proactive and as targeted as we can be in detecting their presence," he said.
Mueller said transportation systems and nuclear power plants remain key al Qaeda targets.
James Loy, acting deputy secretary of homeland security, agreed. In a written statement, he said that despite the efforts of the U.S. intelligence community and his department, and advances in information sharing, technology and organization, "any attack of any kind could occur at any time."