They didn't know specifics because they didn't care. They DID know they would be "striking a blow against America and killing Americans",and that's all they needed to know to volunteer.
So how can some Afghani running around in the hills be aware, much less responsible?
You ain't been paying attention,have you? They teach holy war in their mosques,and pray for your destruction several times a day. This is what is uniting them.
That's complete nonsense. 99.9% of Muslims get up in the morning and wonder what's for breakfast just like you and I do.