In islam you can fight in self-defence or in order to preach your religion. Bin Laden is fighting purely in self-defence, he isnt the ones constantly attacking and starting new conflicts and wars. The only officially confirmed attack by al-Qaida is the 9/11, but why do you considere those people who died for innocent civilians? Those same people who died were the people who payed their government millions of dollars, money that was later used to kill muslims.
I'm not saying that it justefies the attack, but I'm saying that those 3000 who died were in fact not innocent civilians! They chose to live in america, and therby chose to pay the forces that traumatize every muslims life, they could have simply left america but they chose not to!
They were not innocent civilians, they were the wheels holding and moving the car forward. A civilian is someone who do not support his governments actions in any way, those people clearly did!
The prophet talked at a age were you could chose who to kill and who not to! Today people dont fight with swords, you cant specifically chose who to kill and some times unarmed people will be killed. Now al-Qaida has no army what so ever, so how are they supposed to fight back otherwise?