The real lesson of Vietnam was how to fight a war you can't win. The very first premise is to understand that 'they' are not going to actually use their weapons. 'They' could obliterate you but they will not. Once you understand that you can suspend the ultimate worry. No nukes are coming. 'They' are going to worry about human right.
Once you have realized that their weakness is really 'human rights' all you need to do is exploit that weakness. That is what Ussama understands. When he says you don't have the guts to fight that is what he means. That is why terrorism works. How are you going to change that?