Al-Qaida can be expected to attempt an attack on the United States in the next three to six months, senior US intelligence officials told Congress today.
The terrorist organisation is deploying operatives to the United States to carry out new attacks from inside the country, including "clean" recruits with a negligible trail of terrorist contacts, CIA Director Leon Panetta said.
Al-Qaida is also inspiring homegrown extremists to trigger violence on their own, Panetta added.
The annual assessment of the nation's terror threats provided no startling new terror trends, but amplified growing concerns since the Christmas Day airline attack in Detroit 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-Qaida is adapting its methods in ways that oftentimes make it difficult to detect," Panetta told the Senate Intelligence Committee.
Al-Qaida is increasingly relying on new recruits with minimal training and simple devices to carry out attacks, the CIA chief said as part of the annual assessment of national threats provided to Congress by the top five US intelligence officials.
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."
The hearing comes just over a month since a failed attempt to bring down an airliner in Detroit by a Nigerian suspect.
The assessment follows only a few months since US Army Maj. Nidal Hassan is accused of single-handedly attacking his fellow soldiers at Fort Hood, Texas, killing 13.
Director of National Intelligence Director Dennis Blair described Hassan as homegrown extremist. He also said that al-Qaida can be expected to continue and try to attack the United States until Osama bin Laden and his No. 2, Ayman al-Zawahri, are dead.
The US still does not know the intended targets of suspected terrorist Najibullah Zazi, who was arrested in September and charged with plotting to attack New York City with homemade bombs, Blair said.
He warned as well of a growing cyber threat, saying computer-related attacks have become dynamic and malicious.
Obama has promised to make cyber security a priority in his administration, but the president's new budget asks for a decrease in funds 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 physical 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.