“Delivering democracy to the Muslim world” has been the Orwellian rhetoric used to mask Bush-Cheney’s application of pressure and force, its dramatic attempt at reshaping the Pakistani government (into a joint Bhutto/Sharif-Musharraf) coalition, and backdoor plans for a military intervention. Various American destabilization plans, known for months by officials and analysts, proposed the toppling of Pakistan's military.
The assassination of Bhutto appears to have been anticipated. There were even reports of “chatter” among US officials about the possible assassinations of either Pervez Musharraf or Benazir Bhutto, well before the actual attempts took place.
As succinctly summarized in Jeremy Page’s article, "Who Killed Benazir Bhutto? The Main Suspects", the primary suspects are 1) “Pakistani and foreign Islamist militants who saw her as a heretic and 
The assassination of Bhutto has predictably been blamed on “Al-Qaeda,” without mention of fact that Al-Qaeda itself is an Anglo-American military-intelligence operation.
More about Inter-Services Intelligence on Wikipedia:
"Critics of the ISI say that it has become a state within a state, answerable neither to the leadership of the army, nor to the President or the Prime Minister. The ISI has been deeply involved in domestic politics of Pakistan since the late 1950s. The 1990 elections for example were widely believed to have been rigged by the ISI in favor of the Islami Jamhoori Ittehad (IJI) party, a conglomerate of nine mainly rightist parties by the ISI under Lt. General Hameed Gul, to ensure the defeat of Bhutto's Pakistan Peoples Party (PPP) in the polls."