Terrorism is difficult when the target is 8000 miles away. Going to where they are provides incentives for them to act locally.
What hasn't happened is another terrorist attack on U.S. soil. It's more like trying to dismantle a wasp's nest with your bare hands. You'll get stung, but it will be harder for wasps to get around and sting others.
For what it's worth, the situation seems far too complicated to be distilled to a handy soundbite. As much as I'd like to say "They respect only strength," I think shootinstudent has a point in that such a statement is not enough to fully describe their behavior, even though it may help.
At this point, it looks like Obama is going to act the way he said he was going to in his campaign: He wants to try a more diplomatic approach. I suppose time will tell whether or not this was a good move. Unfortunately, the proof that it is a bad move would be thousands of dead Americans. It would be great if simply going to Muslim countries and talking to the people (who aren't terrorists) made those intent on terrorism less so. I worry that it will not, that the terrorists will simply call this another "attempt" by "America" to "subjugate their people", and that other shifts in policy might indirectly result in another catastrophe.
I mean, does anyone expect bin Laden or whoever to post a video the day after, saying, "It looks like the imperialist American scum have acquiesced to our wishes for independence, so no more terror, guys, seriously." I suspect the video would have much more of the tone I stated above, namely, that "President Obama's attempt to sugarcoat the subjugation... etc."
Terrorist groups have myriad motivations and rationalizations for what they do. Some might want America completely out of the Middle East. Others might want to see the end of Israel. The motivations will be as numerous as the groups. Unfortunately, Obama's policy results in neither of these demands being met. What reason, then, would a terrorist group with such a goal have for abandoning terror tactics? I argue that a speech by Obama, even a really good one, that has the people cheering, gives these terror groups no reason to give up.
Sorry about the length.