In a video message on Sunday, the group said it carried out the attack, in what would be the first time it had been known to strike outside South Asia. US officials quickly cast doubt on the claim, but the arrest of a Pakistani-American in New York who allegedly has admitted to being trained in the group's heartland in Waziristan has given it new credence.
Maj. Gen. Athar Abbas, the military's chief spokesman, said the claim should be “taken with a pinch of salt.” “Anybody can claim anything, but whether the organization has that kind of reach is questionable. I don't think they have the capacity to reach the next level,” he said.
The attack may increase pressure on the Pakistan Army to launch a new offensive in the northern part of Waziristan, something it has been avoiding until now. US and European officials have long said that many of the terror plots in the West are hatched in the region.
Abbas declined to comment on reports that the suspect, Faisal Shahzad, had been to Waziristan for training.
Pakistan intelligence officials say they have detained several people for questioning since Shahzad's arrest, but it is unclear if they are believed to have played a role in the plot.
The army had claimed to have delivered the Pakistani Taleban a decisive blow in an operation late last year in South Waziristan. But the notion that the Pakistani Taleban are on the ropes has been shaken by continued bombings in Pakistan, the emergence of videos of a top commander previously believed to have been killed, and the group's claims of responsibility for the Times Square bomb attempt.
In an undated letter obtained Wednesday by The Associated Press, the commander, Hakimullah Mehsud, threatened attacks on America and Pakistan in retaliation for the conviction in the United States of Aafia Siddiqui, a 37-year old Pakistani scientist.
Siddiqui was convicted in New York in February of trying to kill American service personnel after her arrest in Afghanistan in 2008. Her case has triggered anger among Pakistani groups and in sections of the media, where she is portrayed as innocent.
The letter is addressed to Siddiqui's sister, Fozia, who is campaigning for her release.
“We are with you in the pain you have suffered in connection with Aafia Siddiqui. God willing, we will give a reply to America and the cruel rulers in Pakistan in such a way they will remember for their whole life.” The letter was given to the AP by a reporter for the local TV station that first reported its existence.
The reporter said it was seized from an arrested aide to Hakimullah and never reached Fozia.