Yea, but this only causes them to use a different type of detonator, such as a timer or a homocide bomber.
Right, keep them off balance. Let them know that we don't just let our people be sitting targets.
Any plan they come up with will be scripted to death since they will have spent years getting it done. A little interruption or alteration will work wonders and keep them busy creating new plans.
They will find that they are not able to skirt every option available to Homeland Security and people willing to be innovative to counter attacks on the fly.
Did you notice that England immediately shut down the entire transportion system after the attack? Why did they do that? To prevent the possible consecutive attacks all through the system.
Now, the purists here will complain - well, those that have to stop their whole transit system for freedom, do not deserve freedom.
And, again I say - so very glad such people are not protecting us - we would be slaughtered massively.