Al-Qaeda's Yemen-based wing is reported to have what it calls a "strategy of a thousand cuts" to hurt the U.S. economy with frequent small-scale attacks.
In an online magazine, the group al-Qaeda in the Arabian Peninsula said such methods against U.S. targets would be a cheap way to "bring down America."
The group said it can play on what it calls the "security phobia that is sweeping America."
The strategy, also referred to as Operation Hemorrhage, could further weaken the U.S. economy by increasing security costs, the group said.
The new threat was published Saturday in a special edition of Inspire magazine, an English-language propaganda publication produced by al-Qaeda in the Arabian Peninsula.
The article also said it had cost just $4,200 US to work out the plot to mail two parcel bombs to the United States from Yemen late last month. Even though the bombs did not explode, the group said the security scare made the plot worthwhile.
Printer toner cartridges containing explosives were intercepted in central England and Dubai before they could be detonated or arrive at their reported destination, a synagogue in Chicago.
The chair of the U.S. Joint Chiefs of Staff said Sunday he believes the group will try to carry out more inexpensive, small-scale attacks. Adm. Mike Mullen said the group has grown and is dangerous, and counterterrorism efforts should focus on its activities.