In any case, we must see and accept our own limits in what we can and cannot do about the sources of terrorism and within those limits do what we actually can and should to mitigate the problem. Finally, we must recognize above all that it is not just our problem, but mainly their (the ruling classes of the countries that are the sources of terrorism) problem; they have to fix it, and they may, or they may not. Either way, we have to live and deal with it as best we can.
I took the above as a succinct, pragmatic assessment. The point of discussion I was trying to get at is the need for a more sober and responsible assessment of what we can and should do. By that, I mean proactive effort to alter the situation in a timely manner, with military force if necessary, and not the endless, inactive deploring that seems to be the norm.

e.g. Queen Victoria deplored the sub Saharan slave trade, but she also sent Chinese Gordon to Khartoum to try and end it. (Her Majesty might also have sent a bit more in the way of troops for him to do it with, but that's another topic.)