Some 24 hours after a grenade and a powerful bomb tore through two-time Pakistani prime minister Benazir Bhutto’s cavalcade through the streets of Karachi, no group has claimed responsibility for the attack.

Bhutto, who returned to Pakistan Thursday after eight years in exile, was herself uninjured. But the bombing has been labeled the worst terrorist attack in Pakistani history. Most of the 136 dead and hundreds injured were members and supporters of Bhutto’s Pakistan People’s Party (PPP), including fifty members of a PPP security detail.

Pakistan’s US-backed, military-controlled government has blamed the attack on Islamic fundamentalist terrorist groups—the Taliban, al-Qaeda, or one of a number of likeminded Pakistani-based groups.

In recent weeks several of these groups did publicly call for the assassination of Bhutto, who has won the Bush administration’s backing by calling for Pakistan’s security forces to launch a merciless campaign to assert control over the tribal areas adjacent to Afghanistan and by agreeing to ally with General Pervez Musharraf, who seized power in a 1999 coup and has provided pivotal logistical support for the US occupation of Afghanistan.

At a press conference Friday, Bhutto challenged the government’s assertions concerning responsibility for the Karachi bombing. Whilst conceding that Islamic extremists may have carried out the attack, she insisted it had been orchestrated by “certain individuals who abuse their positions.”

Bhutto added that she had recently sent a letter to President Musharraf, giving the names of people in the government and Pakistan’s security forces who have been conspiring against her.

Earlier, Bhutto had told the French magazine Paris-Match, “I know exactly who wants to kill me. It is dignitaries of the former regime of General Zia who are today behind the extremism and the fanaticism.”

Zia—who overthrew Bhutto’s father, Zulfikar Ali Bhutto, then had him hanged—led a brutal dictatorship that, at Washington’s bidding organized mujahedin to fight Soviet forces in Afghanistan, till his assassination in 1988.

Bhutto was careful, however, not to implicate the Musharraf regime or the military high command in the attack, thereby distancing herself from remarks made by her husband, Asif Ali Zadari, who remains in Dubai.

In the hours immediately after the bombing, Zadari told Geo television, “I blame the government.” He added that the PPP would have to rethink its understanding with the Musharraf regime.

Bhutto has called for an inquiry into why street lights along the route of her procession from the Karachi airport to the mausoleum of Pakistan’s founding father, Mohammed Ali Jinnah, were shut off hours before the attack was launched. “As the sun set,” explained Bhutto, “we saw that the street lights had been closed. Our security guards were having a difficulty in identifying suicide bombers... because we couldn’t see.”

In addition to Bhutto’s own extensive security detail, the government mobilized thousands of security forces to protect the PPP procession.

There continues to be much confusion over how the attack was organized. Bhutto has said that there were as many as four attackers. But the Home Secretary of Sindh, Ghulam Mohatarem, told a press conference Friday that the attack was carried out by a lone suicide bomber.

According to an article in Friday’s Dawn, survivors of the attack thought the explosion had come from a police van and started abusing and attacking government security forces.

News accounts indicate that it is now accepted that the reason the police vehicle appeared to have been the source of the explosion was that it had blocked the suicide bomber’s path toward the armored truck in which Bhutto was riding and thus took the brunt of the explosion.

It is certainly possible that the bombing was orchestrated by sections of Pakistan’s military-security establishment who resent the many shifts Islamabad has had to make in its geo-political posture—including withdrawing its patronage of the Taliban regime in Afghanistan in September 2001 and scaling back its use of Islamicist insurgents against India in Kashmir and elsewhere—to accommodate Washington’s demands. Under US pressure, Pakistan has mounted a counter-insurgency campaign in Waziristan that has resulted in heavy military losses, to say nothing of civilian casualties, and repeated refusals on the part of Pashtun soldiers and officers to fight their Pashtun-speaking brethren.

But the list of those who might have sought to eliminate Bhutto does not stop with Islamacist terrorists and insurgents and sections of the military-security establishment who have patronized them or even with other sections of military who feel threatened or aggrieved by the reconfiguring of Pakistan’s government.

Many of Musharraf’s allies, especially in the leadership of the military-sponsored PML (Q), are known to have vigorously opposed a power-sharing deal with Bhutto as they rightly fear it will result in their marginalization.

The administration of Karachi and the province of Sind, of which Karachi is the capital, are led by the Muttahida Quami Movement (MQM), which was had violent clashes with the PPP in the past. It was the MQM, acting with the blessing of Musharraf, that last May 12 and 13, mounted violent attacks on PPP supporters in Karachi that left more than 40 dead.

The bombing has served to exacerbate an already highly charged political situation.

The Bush administration managed to broker an understanding between Musharraf and Bhutto on the eve of the October 6 sham presidential election, thus ensuring that the PPP would not join the other opposition parties in challenging the election’s legitimacy by ordering its legislators to resign. But huge differences remain over the powers of the president and while Bhutto has indicated she wants to become prime minister after elections slated for next January that would require amending the constitution to abolish a prohibition on persons serving than two terms as prime minister.

Musharraf had appealed to Bhutto to delay her return until the Supreme Court rules on the constitutionality of last month’s sham presidential election and his standing for the presidency while remaining head of Pakistan’s armed forces.

Musharraf, his aides and cronies have repeatedly suggested that should the Supreme Court rule against him—which is unlikely given the court’s long history of sanctioning the military’s trampling of democracy, but not impossible in light of the intense divisions within the Pakistani elite—he will invoke emergency law.

But Bhutto chose to defy Musharraf in the hopes that by demonstrably asserting her independence she could staunch the loss of popular support that has resulted from her consorting with the military regime.

At Friday’s press conference, Bhutto declared “For me, the attack was not on an individual, the attack was on what I represent—it was an attack on democracy, an attack on the very unity and integrity of Pakistan.”

The reality is that Bhutto’s shaky deal with Musharraf is a travesty of democracy.

It was brokered by Washington, which has a decades-long history of sustaining military rule in Pakistan, in pursuit of US imperialism’s predatory ambitions in Central Asia and the Middle East.

The deal was sealed with a National Reconciliation Ordinance that gives an amnesty to Bhutto and numerous other corrupt Pakistani politicians, and, to the satisfaction of the Bush administration, entrenches, in the person of Musharraf, the leading role of the military in Pakistan’s governance for years to come.

Bhutto’s motivations are two-fold. She is anxious to get a share of power and patronage. But even more importantly, she is seeking, as she has herself repeatedly said, to avert a wave of street protests that could spin out of the control of the political elite and destabilize the military.

The Bush administration, for its part, is looking to Bhutto to give increased popular legitimacy to a reconfigured Musharraf regime—one in which there will be a better civilian façade for a government in which the military and Washington will continue to wield commanding influence and that, therefore, will remain a linchpin of US interests and aggression in the region.