America should not attack Iran but they shouldn't have invaded Iraq or Afghanistan as they did either. The excuses at the time were poor and the excuses used to remain are equally poor. The only thing this time is that there has been a longer build up to any attack and threats have been made. Iraq and Afghanistan were attacks made with no planning, no exit strategy and has been poorly run in between.
The attack has been with minimal numbers, with little support and with minimal equipment. The wars have rapidly lost support as the body count has risen. Any further attack on a far off country that forms no threat to America will find itself with little or no support.
Iran's basic crime is to have nuclear facilities that they seem to have hidden, the theory being the factory isn't a power station as claimed but a bomb factory. The facts seem to indicate that whatever is true, there are no bombs and there is no imminent threat to anyone.
It could be argued that a preemptive strike is a good idea but that could be used for a number of places that may cause a problem some time. Also the public will see the dictatorship in Zimbabwe as one of many places that would warrant an intervention.
It will see that rather then moving the soldiers back home to retrain and rest, that they are simply moving next door. That could be used both ways though as it saves time and money, saves massive troops and equipment movements and means a fighting fit force is ready. This argument would be a plus if the attack was in any way justified, as its not, the troops should get out of Iraq and Afghanistan and get home.
The morale will be low due to the length of time spent in theatre and due to the excessive losses. The recruitment of new soldiers will also be a struggle with news of deaths and spending 9 months or more thousands of miles from home.
The whole military needs to reconvene at their respective bases, to rest and recuperate and to rebuild. The equipment needs to be overhauled or replaced. The years in deserts will have caused a lot of damage that presumably hasn't been fixed properly in the field.
Many items will have been damaged irretrievably or totally destroyed and will need replacement, hopefully with better designed equipment where failures have been found while in use.