Useful history:
Bin Laden has plotted against Bhutto since she first became prime minister of Pakistan. In the fall of 1989, in the lead up to a crunch no-confidence vote in Pakistan's parliament, Bin Laden, based then in Peshawar, tried to sway the outcome by sending money to Islamabad to buy votes. According to testimony in Peter Bergen's 2006 oral history The Osama bin Laden I know, Bhutto, on discovering Bin Laden's involvement, personally phoned up King Fahd of Saudi Arabia and demanded the Saudis rein him in. The Saudis called Bin Laden back for consultations and promptly confiscated his passport, cutting him off for a while from the al-Qaida organisation he had founded in Pakistan the year before. The episode presumably did not endear Bhutto to Bin Laden.