Islam condemns the killing of civilians in war. In peace this kind of act is judged as nothing but murder. I am not convinced that Usama bin Laden, alone, is behind these attacks but it is not in dispute that he welcomes such attacks.
Usama bin Laden has declared war on the US (and her allies) on behalf of all Muslims claiming that the US is already at war with all the Muslims - this claim being based upon US actions in various parts of the Muslim world including for example the hundreds of thousands of soldiers and civilians killed in Iraq by war and then sanctions.
The judgement of a large majority of the Muslims worldwide is that his analysis is wrong and that the conclusions he draws from it are wrong too. Therefore, the Muslims as a whole reject this declaration of war.
I can only see one way in which his analysis could gain credibility. That is, if the US government wages wars against Muslim communities who put obeying God above obeying the US or if the US government wages indiscriminate wars against Muslim populations. This danger is all too real.
Muslims around the world condemn this attack.
"Who, then, is behind these attacks?" You may well ask. I don't know, but here is a link to an alternative and credible explanation of current events:
The Real Culprits?