> The thing that mystifies me is that U. S. war planners "theoretically knew" this, too; at least, I would assume.

They would have, because this has been wargamed and written about for decades. It's playing out exactly as expected, which is why no US administration until this one was willing to go to an outright hot war with Iran. Unfortunately, this war dept and admin has a staggering amount of hubris, incompetency, and a strange devotion to carrying out every whim of a certain semi-allied state I won't name directly but can be inferred.