FBI officials are reviewing travel records from Africa to determine if terror operatives trained in Yemen have already made their way to the United States as top intelligence chiefs warned that an attempted al Qaeda attack against the United States is a high possibility in the next three to six months.
"We judge that al Qaeda maintains its intent to attack the homeland -- preferably with a largescale operation that would cause mass casualties, harm the U.S. economy or both," National Intelligence Director Dennis Blair wrote in his annual threat assessment for the House Permanent Select Committee on Intelligence today.
Blair told the Senate Select Committee on Intelligence Tuesday that an attempted attack "is certain."
CIA Director Leon Panetta and FBI Director Robert Mueller told the Senate committee they agreed with Blair's stark assessment, explaining that it is becoming more difficult to identify the threat posed by an evolving al Qaeda, which has become more reliant on its regional terror networks to conduct attacks.
Some of the intelligence about purported attacks has come from alleged Christmas Day bomber Umar Farouk Abdulmutallab, who, officials said, is providing "useful, actionable information" to the FBI.
Intelligence from the suspect and other sources indicate that there are other people like Abdulmutallab who were trained in Yemen and not all killed by the U.S. raids there in December, ABC News consultant and former counterterrorism official Richard Clarke said.
"There are people like him who we don't know their names, we don't know what they look like, but they probably don't look like our stereotypical view of an Arab terrorist," Clarke said on "Good Morning America" today. "We may not even know what country they're from -- they may be British, they may even be American -- who are out there and that probably means there will be another attempt."
Despite the sobering assessment from the nation's top intelligence chiefs, Clarke said, another attempt does not necessarily mean there will be another successful attack.
"We shouldn't panic here," he said. "CIA directors always say this once a year in an annual threat briefing. And they always predict there's going to be another attempt. Another attempt does not mean another successful attack, so we shouldn't all head to our bunkers."
Blair today shot down ideas that threats of homegrown terror may be on the rise.
"It is clea r... that a sophisticated, organized threat from radicalized individuals and groups in the United States comparable to traditional homegrown threats in other countries has not emerged," he wrote in his testimony. "Indeed, the elements most conducive to the development of an entrenched terrorist presence -- leadership, a secure operating environment, trained operatives, and a well-developed support base -- have been lacking to date in the United States or, where they have been nascent, have been interrupted by law enforcement authorities."
Blair did warn House members of "malicious cyberactivity" by terrorists.
"The United States confronts a dangerous combination of known and unknown vulnerabilities, strong and rapidly expanding adversary capabilities, and a lack of comprehensive threat awareness," Blair wrote in his threat assessment. "Malicious cyberactivity is occurring on an unprecedented scale with extraordinary sophistication."