Trump was given a 'menu' of options
for the Iran strike that included ships, missile facilities, and militia groups - of course Fatass Trump choose the extreme option.
Actually Trump has pulled back several times - a consistent problem with him when dealing with Iran is that he has been, if anything, timid, and they perceived that this administration - like the previous one - no longer had red lines it is willing to enforce.
If we had reacted to the downing of the U.S. Drone and attacks against shipping back in the summer more strongly, we probably wouldn't be in this position now. But, we pulled back at the last second and, so, here we are.