If we waited until the end.
One of the things that encouraged Bin Laden and according to his own words caused him to embark on the strategy of taking swipes at us and even to provoking open war, was that we kept backing down and taking the easy way out. He became convinced that we were "too decadent" to defend ourselves for long.
Further, as Clinton's terms went on, a major selling point for our destruction was that we tolerated Clintons behaviour.
My guess is that they expected Gore to become president and nothing would change.
They could attack us at will.