Surgical strikes aren't feasible, because we aren't sure where to hit.
Invasion isn't feasible because Iran would be tougher than Iraq, and we couldn't even make that work. Iran is mountainous, armor would be of little use, and the effectiveness of air power is greatly reduced in mountainous terrain. Nobody is foolish enough to expect songs and flowers this time, it would be spirited resistance the whole way way in. Now if the Iraqis could defeat 150,000 US troops, it's pretty clear we don't have the manpower to take on Iran and win.
I've heard people say that the only feasible operation that would guarantee we took out their capability would involve inserting large numbers of troops quickly to secure the nuclear facilities, destroy them completely and then leave quickly. This operation would be fraught with risk, and undoubtedly it would incur high casualties, and the possibility of devastating failure would be very high,
and there is a real question as to whether the military is capable of pulling it off.