http://www.csmonitor.com/2004/0325/p01s01-usfp.html
In the spring of 1998, a unit dedicated to Osama bin Laden at the CIA’s counterterrorism center hatched a plan to snatch the Al Qaeda leader, who by then had declared war on the US.
[…]
The plan called for a midnight raid of the compound through a drainage tunnel. An attack party of 30 fighters would emerge from the desert floor, scour the buildings for the terrorist leader who was believed to be sleeping with one of his four wives, and then spirit him away in a convoy of motorcycles.
The plan, however well conceptualized, was never approved. The reason: the likelihood that innocent bystanders would be killed. It was one of at least four opportunities the CIA identified in the late 1990s to either capture or kill the most infamous terrorist in the world.