The problem is, when someone does that, it leaves the impression that you are capable of repeating that and doing much more. In W's case, he got so much static because everyone believed that if we were messed with, he would attack.
In Obama's case, though, I think he's doing it to create a false impression, and he's too clever by half. He is so confident that he believes he can outwir everyone's expectations. By killing fifteen here and thirty or one hundred here and there early on, combined with his Gitmo and "torture" policies, he's trying to create the impression that he is just as capable of delivering an ass whuppin as Bush but he has a "UN-friendly" side.
He is doing this now so he has cover for when he pulls us out of Iraq and presses on in Afghanistan.
It could work. Just because I can't stand the guy doesn't mean I hope it doesn't. But it depends on knowing what your opponent thinks, and what he thinks of you. It could very well lead to more "testing" i.e. terrorists trying to sneak things onto planes not to destroy them but to see if it can be done, suicide attacks, etc.
At this stage, that not knowing is a new president's biggest weapon. But personally, I don't think his previous decades on the planet are meaningless. He hasn't become some kind of hawk. Maybe the daily briefings he's been getting have convinced him to try to create that impression. But...I don't know.
It’s certainly baffling to me. I just don’t understand the fine points of political maneuvering. It’s like an intense game of chess and I was never good at that game either.