Times Square bombing's Pakistan-born suspect Faisal Shahzad received instruction from the Pakistan Taliban's suicide-bomb trainer, the Wall Street Journal reported citing a senior Pakistani official.
If verified, the suspected links between Pakistan Taliban and Shahzad would mark a stark shift in how it and related jihadist groups, which have so far focused on attacks within Pakistan and in India, not the US, pursue their goals, it said.
Pakistani investigators are also probing Shahzad's possible connections with Jaish-e-Muhammad, an outlawed Islamist militant group, after the arrest Tuesday of Tohaid Ahmed and Mohammed Rehan in Karachi, the Journal said.
The two men were believed to have links to Jaish, it said citing a senior Pakistani government official. Ahmed had been in email contact with Shahzad;
Rehan took Shahzad to South Waziristan, the official was quoted as saying. There, Shahzad received training in explosives in a camp run by Qari Hussain, a senior commander with Tehrik-e-Taliban Pakistan who trains suicide bombers, the official was quoted as saying.
Hussain is also a cousin of Hakimullah Mehsud, the Pakistan Taliban's chief. The 30-year-old Shahzad has admitted to investigators that he received training from militants in Waziristan, US officials said.
Hussain claimed responsibility for the attempted attack in a weekend audio message. His message followed a video of Mehsud, the Pakistan Taliban leader, in which he warned of a wave of attacks on the US "Our fighters are already in the United States," Mehsud said.
US and British intelligence officials estimate that about 100 Westerners have in recent years taken advantage of lengthy trips to the region to complete training at jihadi camps in Pakistan and returned to their home countries, the Journal said citing Bruce Hoffman, a terrorism expert at Georgetown University.
That figure includes Najibullah Zazi and a key Mumbai attack plotter David Headley, who recently pleaded guilty in the US in terror cases, and numerous British terror plotters.
It also includes Shahzad, who told border officials in February 2010, upon returning to New York City, that he had been visiting his ailing father in Pakistan.
The size of American and British populations of Pakistani descent is so large that it makes detailed scrutiny of travel overseas difficult. There are more than 200,000 Pakistani-Americans and more than 400,000 Britons of Pakistani heritage.
In the light of the new evidence, the Pakistani army is likely to come under more pressure from its US allies to clamp down on Pakistan Taliban strongholds if strong links with Shahzad emerge, the Journal said citing analysts.