Informants
It seems that most of this kind of information originates from informants of varying degrees of reliability.
I assume that in this case the informant said, "there are 25 of them and they are extremists."
"the information had not been substantiated to the degree that a higher state of alert was being instituted."
I wonder if the guy in the crate from Italy a few months ago was part of this and perhaps even the informer?
