And members of Congress don't want us to go after Iran
They're making noises because they know what's on the way. See post #25.
True, but many of them are just following public opinion. There's no stomach for a real fight with Iran among the majority of Americans.
Much like the Chinese entry into the Korean war, we're just going to pretend that the Iranians aren't really at war with us. The Americans of the time weren't all that interested in being in Korea in the first place, and they certainly didn't want an all out war with China. Pretending that the invading Chinese were volunteers was a conventient fiction for both sides.
What we have now, albiet on a smaller scale, is much the same effect. Iran can fight us without having to fight us. We can't really take the battle to them, due to public opinion, so we pretend along as best we can.