U.S. and Pakistani authorities are investigating who in Pakistan may have had contact with Times Square bomb suspect Faisal Shahzad, and the support they may have given him.
Shahzad has told investigators he received explosives training in the North Waziristan region of Pakistan, a haven for a wide variety of Islamist militant groups. The case highlights the tangle of militant groups operating in Pakistan and how they could have cooperated with a would-be bomber 10,000 miles away.
Among the possible suspects is Tehrik-e-Taliban, or TTP -- the Pakistan Taliban. The organization is different from the Afghan Taliban, but its members have deep empathy with their Pashtun militant brethren seeking to expel U.S. and other foreign forces in Afghanistan.
"They all started off inside Afghanistan, first during the jihad against the Soviets and then the Taliban regime that was fighting the Northern Alliance. So their genesis lies in Afghanistan," says Imtiaz Gul, author of the forthcoming book The Most Dangerous Place: Pakistan's Lawless Frontier.
The Pakistan Taliban's base is now in Pakistan's ungoverned tribal territories, including Waziristan, along the border with Afghanistan. Gul says it wasn't long before the Pakistan Taliban became the handmaidens of al-Qaida there.
"Because al-Qaida had been on the run and once they descended on Waziristan then all of these people found a common ground. And the common ground was the jihad, their so-called jihad against the United States," he says.
The Pakistan Taliban opened their sanctuary to Islamist extremists of all stripes who were inspired by al-Qaida, Gul says.
"They acted also as facilitators. So whoever was interested in coming to Waziristan for training, for inspiration, they received them with open arms. And most of these people basically have been against Pakistan because of its cooperation with the United States," he says.
Stepped-up military offensives by the Pakistani army and intensified missile attacks by U.S. drones have degraded the Pakistan Taliban, analysts say.
But the group's public relations machinery remains intact.
In a video apparently recorded in April and released last weekend, the group's leader, Hakimullah Mehsud, declared that he survived a drone strike that was widely reported to have killed him. He also threatened attacks on the United States.
"The time is very near," Mehsud said on the tape, "when our fighters will attack the American states in their major cities."
Khalid Aziz, the former chief secretary for security in Pakistan's North West Frontier province, says Mehsud is known for his bravado. But Aziz also cautions that Pakistani and U.S. officials should not underestimate the group's ability to manipulate impressionable young people like Shahzad, the Times Square bombing suspect, who may have become disillusioned by life in the West.
Aziz says young, disaffected people with the urge to take action as a Muslim can fall prey to the influence. "Then if there is someone who really wishes to put him around, he can convince him -- that OK, this is the path toward the achievement of your goals. If you can send a youth who cannot determine right from wrong and strap a bomb on him, is this difficult to convince Shahzad to do otherwise? Not at all," Aziz says.
The Pakistan Taliban's potency may have been diminished inside Pakistan, but Gul says the loose alliances that the group has formed with other extremist factions give it a new more dangerous capability.
"What we see right now is an increasing fusion of interest, an increasing alliance between various militant groups, whether in Afghanistan, or Pakistan or elsewhere. They keep facilitating one another. They keep recruiting people and passing them on for the hardcore training and indoctrination in Sudan or Afghanistan or in Pakistan," Gul says.
Aziz agrees that cooperation among extremists has reached a new level.
"There is a full market which is in operation. I've heard of cases where groups buy and sell suicide bombers," he says.
In the mix are group such as Jaish-e-Mohammad (The Army of Mohammad) and Lashkar-e-Taiba (Army of the Righteous) -- groups that were originally sponsored by the Pakistani military to fight with India over control of the territory of Kashmir. Both groups are known to have ties with the Pakistan Taliban.
"They are not very big in numbers, but they are very disciplined. So I think they have fashioned themselves on the lines of regular armies," Gul says.
A spokesman for Lashkar-e-Taiba said Friday that no one from any security agency has contacted the group in connection with the investigation into Shahzad or the Times Square bombing attempt.
The mystery remains, says Kamran Bohkari, South Asia director for the global intelligence firm Stratfor: "Which part of this murky landscape did he plug into?"