You missed the obvious point. Suicide attacks have been our blind-spot since 1945. 9-11 happened because we always assumed they'd plant a bomb, or park one outside, and run. The idea of hijacking an airliner and turning it into a missile was a Tom Clancy plot-point, but not something we ever trained nor war gamed. And I know Iran had nothing to do with 9-11, how about you drop into the conspiracy theory 9-11 board sometime (I used to live there).
As far as Beirut went, the point was it was a suicide bomber who exploited an easy target. The target was easy because we never considered someone would drive a truck into the building, and die with it.
In the mid-1990s my friend and I spun up a consulting group to assess security for private companies. He was ex-military. We'd survey buildings, monitor security for responses, etc. In our free time we war-gamed nightmare scenarios. We gamed destroying bridges in San Francisco Bay, wrecking the airport, cutting of major highways, damaging electrical substations. My masterpiece involved burning a huge chunk of San Francisco to the ground by hijacking a gasoline tanker truck. We were really good at mayhem. But all of our attack involved pulling them off, and escaping to live another day/
But we were humbled on 9-11-2001. Al Qaeda pulled off a masterpiece that continues to pay them dividends. It never occurred to us to use suicide attacks. And we were just like the professionals at every government LE. and intelligence agency: Two Dimensional in a Four Dimensional battlefield.
After 9-11, we added suicide attacks to our assessment, and we found our potential success rate increased. My attack on San Francisco went from two trucks to seven or more with suicide drivers. And the beauty of this was even if the attacks never happen, the US, and other governments have to spend tons of money, and infringe on basic freedoms to have an hope of preventing the suicide attacks. In short, terrorists can win today simple by existing. Even if we kill them, they win...So we kill them. But we deal with Al Qaeda and ISIS on our own terms.
Iran, and their sycophant proxies have been handled discretely since the 1980s. We have always downplayed Iran, being firm when necessary, but never crossing the line. We know they want us to take a swing at them, they always have. We won by NOT blasting away. Now we've unzipped our fly, and Iran couldn't be happier. Trump and Netanyahu took the bait, and Iran being a master baiter, knows other masterbaters when they seem them. The only bright spot in all of this is Russia has been exposed as a crap-fest military force, and their options are mostly non-existent. Too bad Trump's head is up Putin's butt, this could almost be fun.