Bhutto was the target of many militant groups.

Even as Al-Qaeda claimed responsibility of killing Benazir Bhutto there still lays a lot of confusion about the veracity of the claim. She was, in fact, the target of threats from virtually all of the militant groups who make Pakistan their home from al-Qaeda to home-grown terrorists to tribal insurgents on the Afghan border. Her assassination after a rally in the garrison city of Rawalpindi where the country’s military and intelligence services are based also focused anger and suspicion on the government of President Pervez Musharraf.
The former prime minister blamed al-Qaeda, the Taliban and home-grown militants for an Oct. 18 suicide bombing that tore through a procession welcoming her back from exile to lead her opposition party in parliamentary elections. But she accused militant "sympathizers" in Musharraf’s administration of backing the attempt on her life. Bhutto’s supporters chanted "Killer, Killer, Musharraf!" outside the hospital where she was pronounced dead Thursday. Musharraf blamed Islamic terrorists, pledging that "we will not rest until we eliminate these terrorists and root them out."
Al-Qaeda No. 2 Ayman al-Zawahri decried Bhutto’s return in a video message this month and called for attacks on all the candidates in the Jan. 8 elections. And according to Bhutto, several Pakistanis arrested in an assassination attempt during her second term in the mid-1990s said they were following Osama bin Laden’s orders. The U.S.-backed, British-educated leader who pledged to redouble Pakistan’s fight against Islamic militancy was also despised by Taliban-style radicals backed by tribes along the border with Afghanistan, where American forces are battling rising militant violence.
Baitullah Mehsud, a tribal warlord in the Waziristan region, was quoted in a Pakistani newspaper as saying that he would welcome Bhutto’s return with suicide bombers. He later denied that in statements to local television and newspaper reporters. Khalid Khwaja, a former Pakistani intelligence officer and self-declared friend of bin Laden, said Bhutto "was very openly threatening these tribal people." "Naturally some of them could have done it," he said. "She was certainly hated to that degree by those elements who are victims of the American terror."
Bhutto also was labelled an infidel by groups such as Jaish-ul Mohammed, Lashkar-e-Tayyaba and Hezb-ul Mujahedeen, which were spawned by Pakistan’s military and intelligence services to take on neighbouring India in the disputed Kashmir region. The groups later aligned themselves with al-Qaeda and have vowed to battle foreign troops in Afghanistan, and wage war against the Pakistani military for its support of the U.S.-led anti-terror campaign. Some of their leaders said Bhutto deserved to die for her threats to crush militants.
"I think by far the most likely (suspect) is the al-Qaeda organization, which has been trying to kill Bhutto for the better part of the decade," said Bruce Riedel, a senior fellow at the Brookings Institution and former senior director for South Asia on the National Security Council. "If it’s not them, it’s certainly one of the groups that are sympathetic with them," Riedel said. "They all work together and share a common antipathy to Bhutto because she’s a woman, an advocate of secularism, a supporter of democracy and everything they stand against."
Retired army Gen. Hamid Gul, a former head of Pakistan’s Inter-Services Intelligence secret service agency, questioned the security arrangements made for Bhutto’s rally. A cordon of police surrounded the park where Bhutto spoke, yet her attacker was able to get to the rear gate, where he shot her as she was leaving and then detonated himself, according to witnesses. "How could they enter with so much of a police cordon? I am surprised," Gul said. Gul asserted that a suicide bomber couldn’t have carried out the attack without being forewarned of Bhutto’s movements with a cell phone or other device.
"I think it is convenient to put the blame on al-Qaeda. But there are other possibilities and they have to be examined," Gul said, without offering specifics. Gul strongly opposes the U.S.-backed campaign against Islamic militants, and has labeled himself the jihadists’ only public supporter.
A Washington-based friend of Bhutto’s, Mark Siegel, said that the former prime minister had been "very concerned that she was not getting the security that she had asked for," including devices used to jam cell phone signals. "She had asked for special tinted cars, she had asked for four vehicles to surround her at all times," Siegel said. "All of that was denied to her."
In an interview with an international news agency in November this year, a former district leader of Hezb-ul Mujahedeen said some members of Pakistan’s intelligence establishment resented the idea of a woman leading a Muslim nation, as well as Bhutto’s denunciation of militant Muslims. Hezb-ul Mujahedeen is believed to be heavily funded by Pakistani intelligence to fight in Indian-controlled Kashmir. "In the Pakistani (secret) agencies and in the army there are so many people who are not secular, who are fundamentalists and will help a suicide bomber to carry out his job," said the former district leader, Saifullah, who uses just one name. A former Taliban intelligence official, Mullah Ehsanullah, told the news agency that there were more than 500 men training as suicide bombers in 50 sites across the region in Pakistan and Afghanistan. These camps are run by al-Qaeda and include Pakistani jihadists and Arab militants.
U.S. officials in Washington said they were trying to determine who might have carried out the attack. FBI spokesman Richard Kolko said "the FBI continues to work with our U.S. intelligence community partners reviewing the al-Qaida claims for responsibility for any intelligence value. The validity of those claims are undetermined." The statement came after a law enforcement official told the agency that a national FBI and Homeland Security bulletin to law enforcement agencies cited Islamist Web sites as saying al-Qaeda had claimed responsibility. The official asked to remain anonymous because he was not authorized to speak publicly about it. Director of National Intelligence spokesman Ross Feinstein said his agency was "in no position right now to confirm who may have been responsible."