Islamabad, Pakistan:
The Pakistani Taliban, which American investigators suspect were behind the attempt to bomb Times Square, have in recent years combined forces with Al-Qaida and other groups, threatening to extend their reach and ambitions, Western diplomats, intelligence officials and experts say.
Since the group's formation in 2007, the main mission of the Pakistani Taliban has been to maintain their hold on territory in Pakistan's tribal areas to train fighters for jihad against American and NATO forces in Afghanistan and, increasingly, to strike at the Pakistani state as the military pushes into these havens.
Pakistan's military offensives and intensifying American drone strikes have degraded their capabilities. But the Pakistani Taliban have sustained themselves through alliances with any number of other militant groups, splinter cells, foot soldiers and guns-for-hire in the areas under their control.
Those groups have "morphed," a Western diplomat said in a recent interview. Their common agenda, training and resource sharing have made it increasingly difficult to distinguish one from another. The alliances have also added to their skills and tactics and list of shared targets.
"They trade bomb makers and people around," a senior United States intelligence official said Thursday in an interview. "It's becoming this witches' brew."
The senior intelligence official said that in recent years the overall ability and lethality of these groups had dropped, but that the threat to individual countries like the United States had increased somewhat because the groups cooperated against a range of targets.
Not least among the groups is Al-Qaida, which is exerting growing influence over the others. The Pakistani Taliban increasingly serve as its fig leaf, some experts said.
"The Taliban is the local partner of Al-Qaida in Pakistan," said Amir Rana, the director of the Pakistan Institute for Peace Studies, who has tracked militant networks for years. "It has no capacity for an international agenda on its own."
Al-Qaida was one of a number of groups, including the Afghan Taliban, that relocated across the border to Pakistan's tribal areas after the American invasion of Afghanistan in 2001.
The Pakistani military has said for months that it has broken the back of the Pakistani Taliban since it began operations in the Swat Valley, Bajaur and South Waziristan, among other places. But the top leadership of the militant group remains at large and has sought new refuge largely in North Waziristan.
In a video released on Sunday, the Pakistani Taliban claimed responsibility for the attempted bombing. But on Thursday a spokesman for the group disavowed responsibility.
"The Tehrik-i-Taliban Pakistan has had no links with Faisal Shahzad whatsoever," the spokesman, Azam Tariq, said in a phone call to reporters in Peshawar from an undisclosed location. "We never imparted training to him, nor had he ever come to us." The Pakistani Taliban are formally known as the Tehrik-i-Taliban Pakistan.
But he did reiterate the claim of the Pakistani Taliban leader, Hakimullah Mehsud, that the group had placed suicide bombers in the United States, who, he said, would carry out their mission at an opportune time.
The Pakistani Taliban have tried to instill unity among the tribal and criminal militant groups that sprang up in the border regions. That has met with limited success. But they facilitate all the groups in that they hold territory, particularly in North and South Waziristan, where they run training camps and provide sanctuary.
The various tribes and clans within the Pakistani Taliban tend to be tied to their local areas and do not have the broad reach to recruit and run operatives beyond their territory. "Even Tehrik-i-Taliban is divided into many factions, or every faction has at some level collaboration and coordination," Mr. Rana said.
Still, leaders within the Taliban run training camps in many places along Pakistan's western border area, and it is possible that the bombing suspect, Faisal Shahzad, received instruction there with any one of the groups, analysts said.
"There are training camps all over North and South Waziristan," the Western diplomat said.
The ties between the Pakistani Taliban and Al-Qaida stretch back to the Pakistani Taliban's earliest leaders, said Brig. Mahmood Shah, who served as the senior security official in the tribal areas until 2005.
One of the first, Nek Muhammad, who was killed in an American airstrike in 2004, was known to be a Qaida facilitator, providing logistics and lodging for Arabs in Waziristan.
In 2008, Brigadier Shah said, the Pakistani Taliban leader at the time, Baitullah Mehsud, and Al-Qaida's No 2, the Egyptian Ayman al-Zawahri, met in South Waziristan. That meeting represented an important shift for the Pakistani Taliban, which had until then answered to the Afghan Taliban and militant commanders loyal to Pakistan. "Pakistan told the US that Baitullah Mehsud came directly under Al-Qaida," Brigadier Shah said. "The Pakistani government was very sure that he was Al-Qaida."
The Afghan Taliban leader, Sirajuddin Haqqani, who controls a large fief in North Waziristan, also recently indicated support for Al-Qaida's agenda when answering questions in an open forum on a jihadist Web site, praising jihadi fighters in Iraq and the Palestinian territories.
Adding to the mix, these groups have been fortified by a growing number of militants who have moved to the tribal areas from Pakistan's largest province, Punjab. The Punjabi groups were originally founded and sponsored by the Pakistani military to support the fight with India over the control of Kashmir. But many have turned against the state since the army's siege against militants at the Red Mosque in Islamabad in 2007.
The Punjabi groups have surpassed many of their peers in the technical ability and the viciousness of their attacks. But members can often move among the groups or be members of groups simultaneously, Mr. Rana said. They cross-fertilize each other.
Indeed, it is possible that the Times Square bombing suspect, Mr Shahzad, began his journey to the tribal areas for training by making contact first, possibly in the southern port of Karachi, with militants from one of these groups, Jaish-e-Muhammad.
On Thursday, a Pakistani security official said four Jaish militants, whom he did not name, had been picked up and were being interrogated by American and Pakistani officials.
Yet Mr Shahzad could easily have been recruited or sought out by any one of the Punjabi groups, which have deep influence in Pakistan's cities.
"The kind of knowledge that he demonstrated in his bomb making is very simple knowledge, so how did he come by that? He could have interacted with some militant; it does not need long training," said Hasan Askar Rizvi, a military analyst.
"He may have gone to Waziristan for inspiration or motivation, but did not necessarily get the training there," he added.