Because all the american assets in countries around iran will be "glassed" too, like american bases are already. And then special forces deep in US will start "glassing" US infrastructure, power, water, logistics, etc. (It's not terrorism if you're in war, it's just special units behind enemy lines). Looking at eg. texas, it doesn't take a lot to bring the whole power grid down, especially if properly planned. If you bomb water supply facilities in eg. new york, how many people will you have to evacuate? How hard would it be for those special forces to start forest fires in california? Or poison food supply for the army? Or just bomb a random school in retaliation for the one you guys bombed in iran?

> Why is attacking one's enemies suddenly controversial?

Flying half the planet away to attack someone who in no way endangers you is controversial... it took a few years of vietnam war for americans to figure it out and a few decades to forget it all again and now you're repeating it against a stronger adversary. It's no wonder most of the world hates americans.

edit: looking at his comment history, commenter above me seems to be from israel, not US, but same applies to them too, with the exception of having to ask trump (and the brits and others) for help when iran fights back.