There was a sense of a last inviolacy being desecrated among South Asia's 1.5 billion people and millions in increasingly wealthy and influential diasporas around the world.

Their national cricket teams were above the social chasms that periodically erupt into horrific pogroms. A Muslim like Mohammad Azharuddin could captain the team of Hindu-majority India; a member of a former Untouchable caste like Vinod Kambli could take the field alongside Brahmins; a Tamil like Muttiah Muralitharan could be the star of Sinhalese-majority Sri Lanka.

As the former Pakistan captain turned politician Imran Khan agonised this week, they had been off-limits to the region's numerous terrorists. Worshippers in mosques, churches and temples, busloads of pilgrims, dynastic political leaders such as Rajiv Gandhi or Benazir Bhutto, more humble crowds singled out for ethnicity or social rank: all could be torched, blown up or sprayed with gunfire. But not the demi-gods who walked into the field in Test whites or night-cricket colours, married film stars, sold lucrative endorsements and generated billions of dollars for global TV sports franchises.

Then there was Lahore itself, the dusty city of 10 million that retains the elegance of its Mughal and Raj pasts: the long boulevards shaded by neem and banyan trees, the red stone mosque and fort created by the emperors Akbar and Jehangir, the white Victorian institutions and quaint shops. The elites who gather in their modern villas, dressed in the finest embroidered cotton salwar kameez, sipping fine whisky, discussing the latest books in London and local political gossip; the demi-monde of artists and singers of the love songs known as ghazal or the Qawwali, devotional music of the Sufi mystics of Islam, like the late Nusrat Fateh Ali Khan; the underworld of the city's famed scarlet-lipped, silk-clad whores. How could this city harbour such callous, ignorant evil?

And there was the affront of the attack itself. Up to a dozen attackers appearing from the roadside or blocking the Sri Lankan convoy with stolen cars, producing assault rifles, a rocket launcher and grenades, outgunning a screen of police commandos in a 25-minute battle, then casually melting away into the city, leaving few clues behind them.

What was left at the Liberty roundabout was a traffic jam of conspiracy theories about who was behind the attack. Was it linked to Pakistan's long-running rivalry with India, or the intensifying American pressure on Pakistan's military to crack down on Islamist insurgencies? Was it a bold challenge to the Pakistani state by the sorcerer's apprentices, the Taliban fundamentalists fostered by the Pakistani military's Inter-Services Intelligence directorate, the ISI? Were Sri Lanka's Tamil Tiger separatists, now cornered in a small tract of jungle, making a last nihilistic strike, directly or through proxies?

Was the intensifying fight between Pakistan's two main political parties, the Pakistan People's Party of the President, Asif Ali Zardari (widower of Bhutto) and the Pakistan Muslim League of the former prime minister, Nawaz Sharif, to blame for security lapses? The sketchy images of the attackers, and some circumstantial evidence, point towards Pakistan's military crackdown on Islamist insurgencies.

A popular sub-scenario, that India did it, was quickly aired and then dropped by the Interior Minister, Rehman Malik, despite claims that an official security warning dated January 22 had reported intelligence of an impending Indian operation against the Sri Lankan team. India's spy agencies might have done something like this two decades back. New Delhi now holds the moral high ground after the November 26 attacks in Mumbai, linked to Pakistani-based militants, and has too much at stake in its global ambitions for such ghastly payback.

The alternative sub-scenario is strengthened by recent reports that India had been close to a compromise on divided Kashmir with the former Pakistani military dictator, General Pervez Musharraf, before his grip on power weakened early last year. This would see a convergence of interest between groups focused on Afghanistan and Kashmir disrupting detente with India.

It would give the reluctant Pakistan Army an excuse to break away from its recent campaigns against Taliban bases along the North-West Frontier, and punish the Pakistani Government for arrests of alleged conspirators in the Mumbai attacks. These suspects belong to the banned Lashkar-e-Taiba group whose main raison d'etre is ending India's rule in its part of Kashmir.

The superficial resemblance between the Lahore and Mumbai attackers gives this theory some support: men in their 20s, all wearing backpacks, casually spraying gunfire from the hip. The attack came a few days after four Mumbai suspects appeared in a special anti-terrorism court in Rawalpindi, and a day before the US Federal Bureau of Investigation director, Robert Mueller, arrived in Pakistan to relay evidence on Mumbai collected by Indian and other investigators.

However, the Lahore police chief, Habibur Rehman, initially said the gunmen were bearded and resembled Pathans, the main ethnic group of the North-West Frontier and tribal regions, which suggests more of a Taliban origin than the Lashkar-e-Taiba, which has been based in the Punjab province around Lahore, near Kashmir. Later police released indentikit images of four young men, with thin moustaches or clean-shaven, and said two terrorist groups more closely linked to al-Qaeda, Jaish-e-Mohammed and Lashkar-e-Jhangvi, appeared responsible.

Unless there was some subcontracting, this weakens the third scenario, a Tamil Tiger operation, since their Black Tigers commandos would have been quite distinctive to a local eye from their Dravidian (southern Indian) appearance, quite aside from language problems.

Nor is it yet clear that the Sri Lankan team was the preferred target. Local media reports said the Pakistani team had been due to set off for the Gaddafi Stadium first that morning, but had been delayed a few minutes and the Sri Lankan bus and umpires' vehicle had gone ahead. The Pakistanis have indignantly denied a suggestion by the umpire Chris Broad that they had been tipped off.

Another aspect is that the well-known Pakistani terrorist groups and the Tigers would have pressed home their attack much harder, probably to the point of self-sacrifice. For all the careful preparation and intelligence behind the attack, its execution was a failure, if wiping out the cricket team or abducting its members was the goal.

But increasing numbers of Pakistanis worry that general destabilisation has now become the main game, that the battle for the soul of Pakistan has begun, that militants are starting to lift their eyes from the more backward and isolated tribal regions to the densely populated heartland of Punjab and Sindh.

This month it became evident that Taliban-type militants are close to achieving their goal of imposing a sharia-based mini-state in the Swat Valley, 150 kilometres north of Islamabad. A vicious campaign of intimidation, including beheadings, has shut down video parlours, schooling for girls, and shaving of beards. About 350,000 of the 1.5 million population, including most doctors, teachers, police and government officials, have fled.

The army has baulked at sending enough troops into Swat to clear out just 2500 militants who have imposed this benighted reign. The President has announced that a compromise is being negotiated, with local religious elders rather than the Taliban, to apply a form of sharia. There are reports of a financial pay-off. But will it stop there?

"The phenomenon now is that the Pakistani Taliban have their own agenda for Pakistan. Before, there was a situation where they were an appendage of the al-Qaeda and the Afghan Taliban," the author Ahmed Rashid, the best-known analyst of the Taliban, told the Indian magazine Tehelka.

"The danger is that they will use Swat as a base to spread south of the valley and then closer towards the capital … There have been Taliban attacks in Punjab also. South Punjab is filled with some of these Punjabi groups, who ally with the Taliban. Karachi is filled with both neo-Taliban and Punjabi groups. Certainly there is a big danger of this spreading to other parts of the country very rapidly."

Adding to the mix is the bitter civilian politics. Just six days before the Lahore attack, the Supreme Court disbarred the former prime minister Sharif from political office, over an old charge of ordering the hijacking of an aircraft carrying Musharraf in an attempt to forestall Sharif's overthrow by the military.

Sharif's proxy as Punjab chief minister, his younger brother Shahbaz, was also kicked out of office. The President, Zardari, promptly put the state under charge of its federally appointed governor, who, just before the attack, reshuffled top police jobs.

Sharif's main offence in Zardari's eyes had been to agitate for the reinstatement of the sacked Supreme Court chief justice Iftikhar Chaudhry, who is intent on undoing the pardon given by the departing Musharraf to Zardari for numerous corruption charges during his late wife's terms as prime minister.

The fight will bring mass protests to the streets of Lahore next week, perhaps fatally weakening Zardari's presidency and setting the scene for another army takeover.

Waiting are more terrorists to capitalise on the turmoil. "You can expect much more in the coming days, weeks and months," said an Islamabad journalist, Amir Mateen, who recently reported events in Swat.

"You have thousands of indoctrinated zealots and home-delivery service of every arms that you can think of," he said. "Darra Adam Kehl and Pakistan's tribal areas are the only kind of arms market where you buy things on the shelf, $US100 for the launcher and $US10 for the rocket. You can order them anywhere with a slight transportation fee. With such availability of arms and men you can expect the worst."

Hamish McDonald is the Herald's Asia Pacific editor.