US Attorney General Eric Holder said on Sunday the Pakistani Taliban was behind the attempted Times Square car bombing in New York.
"We've now developed evidence that show the Pakistani Taliban was behind the attack," Holder said in an interview on ABC television's "This Week."
Holder said there was nothing to suggest the government of Pakistan was aware that Faisal Shahzad, 30, a naturalized American citizen born in Pakistan, intended to make the attempt.
Shahzad was arrested last Monday, two days after authorities say he parked a crude car bomb in New York's busy Times Square.
Holder said the Obama administration was satisfied for now with the level of cooperation it was getting from Pakistani authorities in the investigation of the attempted bombing.
In response to questions, he said the administration will have to work with Congress to see whether modifications are needed in the protections given to people who are arrested for alleged terrorist acts.
Some lawmakers have suggested that people accused of terrorism should not have all the rights accorded to those charged with less serious crimes.
Holder said it was important the government have the flexibility it needs to counter acts of terrorism but that any changes have to meet constitutional requirements.