No, it’a Al Qaeda’s responsibility solely.
That said, we could have put a stop to this by now IMO. Imagine if we went back in time to the fall of the Taliban in 2002. Instead of proceeding to Iraq, imagine we had instead increased our military presence in Afghanistan, deposed the warlords and caught Bin Laden. Then we had proceeded to pump funds into Afghanistan, rebuilding the country on the same model we used in Japan after World War 2. By today, Afghanistan would be thriving, freedom and capitalism would be succeeding, and Afghanistan would be turning into the envy of the Arab world.
Sure, easier said than done, but we didn’t even try that route, did we? If this had come to pass, would Al Qaeda still be such a successful organization? Would the radical fringe of the Islamic world still be dedicated to our destruction? I submit that this would have gone a long way towards winning the hearts and minds of those who are currently our enemies. Instead we went down a route that has made us less safe, not more.
I lay the blame for this incident entirely at the feet of Al Qaeda. At the same time, I also hold our leaders responsible for doing a lousy job of fighting the war on terror. I hold us all responsible for allowing our leaders to continue down this path. We all need to be smarter than we have been, and hold ourselves to a higher standard. What we are doing is not working.