What is differentiates a country that willingly harbors terrorist to one that doesn't? Does anyone have a solid article or statistics that can present this information to me? I kind of browsed through google, and couldn't find anything (but I am at work.) What if the country doesn't have the means to get terrorists out of their country?

I'm sure there are some terrorists in the US... so should we attack ourselves? (sorry for that sarcastic statement). It just seems to me everything is so vague when it comes to who is defined as a country that is a safehold for terrorists.