Last updated 6:30 p.m. ET
Al Qaeda can be expected to attempt an attack on the United States in the next three to six months, senior U.S. intelligence officials told Congress on Tuesday.
The terrorist organization is deploying operatives to the United States to carry out new attacks from inside the country, including "clean" recruits with a negligible trail of terror contacts, CIA Director Leon Panetta said. Al Qaeda is also inspiring homegrown extremists to trigger violence on their own, Panetta added.
"There is the opportunity and chance that al qaeda will be sending networked individuals, trained individuals in particular from the regional affiliates but there's also the potential of radicalized inspired lone wolves trying to attack using simple methods," said CBS News security analyst Juan Zarate.
"I think the challenge for the intelligence community, and part of the worry that the intelligence specialists expressed;p they're not sure," Zarate told "Early Show" co-anchor Harry Smith.
The annual assessment of the nation's terror threats provided no startling new terror trends but amplified growing misgivings since the attempted Christmas Day airline attack outside Detroit, Michigan, that militants are growing harder to detect and moving more quickly in their plots.
"The biggest threat is not so much that we face an attack like 9/11. It is that al Qaeda is adapting its methods in ways that oftentimes make it difficult to detect," Panetta told the Senate Intelligence Committee.
Several senators tangled over whether suspected terrorists should be tried in civilian or military court. At the same time, a group of bipartisan lawmakers introduced legislation that would force the Obama administration to backtrack on its plans to try Sept. 11 defendants in federal court in New York and use military tribunals instead.
Panetta said the fear is al Qaeda is relying more and more on recruits with little training using simple devices, as in the attempted Christmas day attack, reports CBS News chief White House correspondent Chip Reid.
Panetta also warned of the danger of extremists acting alone: "It's the lone-wolf strategy that I think we have to pay attention to as the main threat to this country," he said.
The hearing comes just over a month since the failed attempt to bring down an airliner at Detroit, allegedly by a Nigerian suspect. The assessment also comes only a few months after U.S. Army Maj. Nidal Hassan is accused of single-handedly attacking his fellow soldiers at Fort Hood, Texas, killing 13 people.
National Intelligence Director Dennis Blair said with changes made since the Dec. 25 attack, U.S. intelligence would he able to identify and stop someone like the man alleged to be the Detroit bomber before he got on the plane. He warned, however, that a more careful and skilled would-be terrorist might not have been detected.
FBI Director Robert Mueller defended the FBI's handling of the Detroit incident, disputing assertions that agents short-circuited more intelligence insights from the Nigerian suspect by quickly providing him with his constitutionally guaranteed right to remain silent.
Mueller said that in "case after case," terrorists have provided actionable intelligence even after they were given their rights and charged with crimes. Mueller said they know such cooperation can result in shorter sentences or other consideration from the government.
Law enforcement officials confirm to CBS News that the Nigerian suspect, Umar Farouk Abdulmutallab, started talking again last week and is.
Hundreds of terror suspects already have been convicted in civilian federal courts, including convicted shoe bomber Richard Reid.
Republican Sen. Lindsey Graham offered a bill Tuesday that would prohibit the government from using Justice Department money to prosecute suspects charged in the Sept. 11 attack in civilian courts.
The move comes in the aftermath of the Obama administration's decision to rethink whether it would try that attack's alleged mastermind, Khalid Sheikh Mohammad, in a New York City courtroom.
The proposed law would cover people who legally could be prosecuted by a military commission, applying to terror suspects who are not U.S. citizens. By Tuesday evening, the bill had support from 18 senators, mostly Republicans.
During the terror assessment hearing, Blair also warned of the growing cyberthreat, saying computer-related attacks have become dynamic and malicious.
Obama has promised to make cybersecurity a priority in his administration, but the president's new budget asks for a decrease in money for the Homeland Security Department's cybersecurity division.
The government's first quadrennial homeland security review states high consequence and large-scale cyberattacks could massively disable or hurt international financial, commercial and other infrastructure.
The report, obtained by The Associated Press, said these types of cyberattacks could cripple the movement of people and goods around the world and bring vital social and economic programs to a halt.