Not until 1998 did al Qaeda undertake a major terrorist operation of its own, in large part because  Bin Laden lost his base in Sudan. Ever since the Islamist regime came to power in Khartoum, the United States and other Western governments had pressed it to stop providing a haven for terrorist organizations. Other governments in the region, such as those of Egypt, Syria, Jordan, and even Libya, which were targets of some of these groups, added their own pressure. At the same time, the Sudanese regime began to change. Though Turabi had been its inspirational leader, General Omar al Bashir, president since 1989, had never been entirely under his thumb. Thus as outside pressures mounted, Bashir's supporters began to displace those of Turabi. The attempted assassination in Ethiopia of Egyptian President Hosni Mubarak in June 1995 appears to have been a tipping point. The would-be killers, who came from the Egyptian Islamic Group, had been sheltered in Sudan and helped by  Bin Laden. When the Sudanese refused to hand over three individuals identified as involved in the assassination plot, the UN Security Council passed a resolution criticizing their inaction and eventually sanctioned Khartoum in April 1996. A clear signal to  Bin Laden that his days in Sudan were numbered came when the government advised him that it intended to yield to Libya's demands to stop giving sanctuary to its enemies.  Bin Laden had to tell the Libyans who had been part of his Islamic army that he could no longer protect them and that they had to leave the country. Outraged, several Libyan members of al Qaeda and the Islamic Army Shura renounced all connections with him.  Bin Laden also began to have serious money problems. International pressure on Sudan, together with strains in the world economy, hurt Sudan's currency. Some of  Bin Laden's companies ran short of funds. As Sudanese authorities became less obliging, normal costs of doing business increased. Saudi pressures on the  Bin Laden family also probably took some toll. In any case,  Bin Laden found it necessary both to cut back his spending and to control his outlays more closely. 
How long after the failed attempt to assassinate Hosni Mubarak did the U.N. impose sanctions on Sudan?
10 months