“Most of the report deals with improbable incidents overseas.”
....a while back they were considering the impact of revolution or national disaster in Mexico...such an event could trigger mass exodus....remember the “boat people” fleeing S.E.Asia in the 70s?....how would we deal with millions of “foot people” streaming into the southwest?...they would have to be stopped at gunpoint...and suppose they resisted at gunpoint?....and suppose their hispanic brethern in the U.S. helped them resist?.
Read the study. It’s interesting. It’s extremely short. And there are elements of the thing, such as dealing with the improbable event, that you can use in your own life. It’s very much like The Black Swan for military ops.
Given the current situation in Mexico, what you describe is entirely possible. MS-13 will instantly become a domestic terrorist group paid by Mexico.