A friend surprised my with the assertion...
Iran hates us and wants us dead. It is a leaning source of trouble in the world. That means they declared war on us many years ago. Someday they will have a nuclear bomb. That means we have to eventually take them out. Today, Ukraine has made Russia too weak to intervene. That means we have a historic opportunity that we have to seize. He's doing a terrible and stupid job but Trump was right to attack Iran. He should do whatever it takes to make it so that they can never project their evil effectively again.
Say I to myself, "Trump, Iran war, stopped clock twice a day? Ouch."
Certainly the basic premise is correct. Iran is bad. Hezbollah, Hamas, Houthis, Oh My!! There's more, too.
Is it possible that this is a good time to start a war? Is it just and ethical since they are enemies. Is the realpolitik sufficiently compelling to override an ethical view opposing it? Will it turn out to be a net good even if it is bad?
I start with the sort of mathematical absolute value of the proposition, net good. To think about that, we need to identify the costs that counter the benefit of taking Iran out of the bad actor equation. It seems that there are four main categories.
1) Money and resources. Hundreds of billions of dollars. Very long resupply for many armaments.
2) Killing and brutalizing people. (I know most people don't care about dead Iranians but I do. Maybe it's ok to kill the Ayatollah but about 1300 people are dead and the entire population is badly harmed.)
3) Making ever more permanent enemies that hate us for even more legitimate reasons.
But my favorite one is...
4) Violation of the international rule of law.
Not only is this invasion against the law, it tells everyone else that the rule of law is optional, non-existent and silly. In every practical and ethical story I have ever heard, it is more important for leaders to be scrupulous about their behavior than for anyone else. When leaders ignore law and decency, that tells everyone else that law and decency are optional if you feel like your reason is important enough.
The United States has just told the world that invading other countries is perfectly fine if you can get away with it. That's what Putin said for Crimea and Ukraine. We were appalled because once that's established as a valid behavior, more and more bad actors will do it... As we see with America following in Putin and Netanyahu's footsteps.
Of course, the first three are important, too.
The money we spend is not available for other uses. Being low on bullets seems quite dangerous with China and Russia and North Korea, and others, active in the world. Certainly many Iranians who were somewhat pro-west are pretty pissed that America has killed a friend or is responsible for their terrified, starving children.
I won't talk about dead people. We all know that Americans don't care about dead Iranians (because the Iranians are right about "the great satan") but we should.
The real problem though is that it will not and cannot work. Suppose we do bomb them back to the stone age and they are neutralized. What happens then? There are sixty million people there that mostly think they are an important country with an important history who have been brutalized and disrespected. Just as installing the Shah set a process in motion that created this situation, this will initiate another process that will certainly be negative.
And that's the optimistic outcome. More likely is that this will be another Afghanistan. After some period of time, we will declare victory and go home having spent a fortune in blood and treasure, leaving behind a population that hates us more fiercely, intent on revenge and as brutal as ever - with a completely legitimate justification. Sure, less infrastructure, more poverty and misery.
Also, a completely sophisticated culture that will set about recreating their power immediately. Iran became an important problem in the nineties, about forty years after the Shah was installed (and that was held back by the fact that the fifties and sixties were very primitive times). There are very, very many reasons to think that the next resurrection supported by modern communications and tech will be much quicker.
There is no just war without an imminent threat (means, "about to happen"). Killing many people today to prevent the possibility of people being killed sometime in the future is unacceptable. I do not accept the idea that 'no wis a good time' in any situation other than, they are on a war footing and it is all but certain we will be killed if we do not act right now.
Putin said that Ukraine is a threat to Russia. Trump says that Iran is a threat to America. There is absolutely no way to distinguish the legitimacy of the subsequent invasions. Objective observers easily see that neither case supports the idea that an attack on us was actually imminent, nor that they were planning some big escalation.
In both cases, the invasions were, at best, a convenient moment to improve the attacker's situation. At worst, based on the intent to kill inferior people and steal their resources.
I continue to believe that invading another country without an absolutely certain and immediate threat is immoral. Invading a large, sophisticated country with a big military and tenacious culture is stupid.