Hmm. I do not have a strong opinion as to what activity the terrorists have been conducting on our soil. How would I know? In the day and age of the Internet, they can do plenty of training and harm here even if the key players stay over there.
Maybe it depends on our modern definition of “training camp.” The 9/11 terrorists were organized. Their main training may have been elsewhere but they had to do some coordination here, if only in small teams.