In a neighbourhood crowded with armed-to-the-teeth Islamist militias, Lashkar-e-Taiba is the deadliest, best-organized outfit on the block.
And it is not without reason that its founder, Hafiz Mohammad Saeed, has been called Pakistan's uncrowned king of terror.
Saeed is a former Islamic studies professor at Lahore University who became radicalized by the Afghan mujahedeen's fight against the Soviets.
He shares the same extreme interpretation of Islam as Osama bin Laden.
Lashkar-e-Taiba means Army of the Righteous and Saeed's oft-repeated goals are to annihilate all Hindus and Jews and then to unite all of South Asia in a single Muslim state. The first step on the road is Kashmir.
But Saeed is not a freelancer.
He founded Lashkar-e-Tiaba during the Afghan/Soviet war of the 1980s with the help of the Pakistani military's intelligence arm, the Inter Services Intelligence (ISI) agency. The ISI provided money, weapons and experienced commandos to train Saeed's religiously motivated volunteers.
Indian and Western intelligence agencies believe the close relationship between the ISI and Lashkar continues to this day.
From Pakistan's first day of independence from British rule 60 years ago, wresting Kashmir from India has been the Pakistan military's obsession.
Kashmir is more than 70 per cent Muslim, but when the British exited in 1949, Kashmir's ruler was a Hindu maharajah who opted to join India instead of Pakistan.
The two nuclear-armed rivals have fought three wars since and there have been countless border skirmishes. The result is a stalemate in which Kashmir is divided by a so-called Line of Control.
And that's where Lashkar comes in.
Indian and Western intelligence agencies believe that Pakistan, having failed to defeat India militarily, continues to train and finance Lashkar to fight a proxy war against Indian troops using terrorist tactics.
Officially, Lashkar is a banned group in Pakistan, a ban forced on former president Pervez Musharraf by the Americans after the 9/11 attacks. The CIA believes Lashkar is closely connected to al-Qaeda. But the effect of the ban appears to have been negligible.
Saeed did resign his position as commander-in-chief of Lashkar, but then founded an Islamic charity he named The Centre for Religious Propagation and Learning. While the centre claims to raise money for the poor, its critics say much the money is diverted to Lashkar.
The centre has a website but you won't find Saeed's picture there.
The stocky 53-year-old with the orange henna beard doesn't like having his picture taken. Islam forbids it, he says. On the other hand, he believes taking human lives is a religious obligation.
The centre's website boasts that since 2000, Lashkar has carried out 98 missions in Kashmir, killing 891 Indian soldiers including three colonels, 10 majors, one commandant, one captain and three engineers.
Suicide commando operations
Lashkar does not typically plant roadside bombs or use suicide bombers like the Taliban and al-Qaeda. Its favoured tactic is suicide commando operations.
Its fighters work in groups of two to five and stage lightning attacks on Indian army bases, taking hostages and firing indiscriminately to kill as many as possible. The fighters do not expect to come back alive.
The tactics are identical to those of the Mumbai attackers, which is why the Indian authorities immediately suspected Lashkar.
Indian police also say traces on cellphone numbers called by the attackers during the attacks reveal calls to a Lashkar military leader in Karachi.
And then there's the confession police say they extracted from one attacker captured alive.
He's the smiling young man in the blue T-shirt caught on the CCTV camera at Mumbai's Chhatrapati Shivaji rail station. His name is Ajmal Amir Kasab.
His interrogators say he admits he is from Faridot village in Pakistan's Punjab province and joined Lashkar a year ago.
He allegedly confessed he underwent two months of indoctrination at Lashkar's Maraz Taib base camp, where he was shown films of India's purported atrocities in Kashmir and fiery lectures by Saeed.
Later that year, Kasab says, he was chosen for an advanced combat course where he did well and was then one of 32 young men selected for marine commando training for the Mumbai mission.
Promise of money for sacrifice, attacker says
He says Lashkar promised to give his family $2,400 Cdn as a reward for his sacrifice.
But while Lashkar may be a willing instrument of the Pakistani military, it appears to be beyond the control Pakistan's civilian government led by Benazir Bhutto's widower, Asif Ali Zadari.
For much of Pakistan's history, real power in the country has rested in the hands of its generals. Every elected government that has strayed from the generals' agenda has been overthrown in a coup.
And in recent months, relations between Zardari and the generals appear to have been strained.
Zadari and Indian Prime Minister Manmohan Singh have been attempting to find a way to settle the festering Kashmir issue peacefully. They have taken small confidence-building measures such as restoring bus traffic over the Line of Control. The generals are reported to fear that Zadari is willing to give away too much.
Many Western security analysts are suggesting that either Lashkar on its own or at the direction of the Pakistan military staged the Mumbai attacks to provoke India into a retaliation that would sink the Kashmir peace talks.
In a desperate attempt to salvage the peace talks, Zadari's immediate response to the massacre was to offer to send the head of the ISI to New Delhi to help with the investigation.
An indication of where the real power still lies in Pakistan was seen when the generals overruled the civilian president and sent a powerless junior officer instead.