At West Point, cadets take a philosophy course in which Augustine's definition of Just War Theory is taught. Discussion is had. Papers are written. This will come up again and again in their careers. The ethics of starting a war and conducting one are hammered home. (thread)
The first part of Just War Theory, the right to go to war--"jus ad bellum"--has the following criteria:
1. There must be "just cause". Innocent life must be in immediate danger, and only combative action can be taken to protect that life.
1. There must be "just cause". Innocent life must be in immediate danger, and only combative action can be taken to protect that life.
2. There must be a competent authority to initiate war. There is supposed to be due process for going to war. Political authorities review available information in good faith within the established legal framework, i.e. our Constitution, war powers, congressional authority.
3. There must be a right intention. War can only be started with a clear purpose that is legally and ethically sound, and military action must align solely with that stated purpose. For example, expanding a mandate to include outside targets w/o evidence is wrong (Iraq).
4. There must be a probability of success for achieving the stated objectives. It is not just to sent troops into a war for objectives you have little hope of achieving out of vanity or pride. War is not a video game.
5. War must be a last resort. All available options must be exhausted before the decision to go to war. This includes diplomatic discourse, the previously mentioned political due process, and less severe military actions. All must come first before the decision to escalate.
6. Finally, war must be proportional. The expected benefits must be equal to the expected harms. War is not a sportsbook. You don't gamble human lives on a marginal benefit.
These are the principles taught to America's military officers. Our modern outlook on Just War Theory is that these criteria boil down to a singular motivation: proportional self-defense against clear, immediate harm or in defense of someone else, all established with evidence.
However, the United States has a long history of starting wars that violate Just War Theory. From the Spanish-American War to Vietnam to the Invasion of Iraq, to say nothing of covert operations we've taken against other governments, one example being Iran in 1953.
That year, the CIA covertly directed Operation Ajax, which overthrew the democratically-elected Prime Minister of Iran, Mohammad Mosaddegh. Why? Because Iran wanted to control its own oil reserves, Britain balked, and Eisenhower feared a communist takeover. It was wrong.
The United States, specifically coordinated by Theodore Roosevelt's grandson Kermit, overthrew Iran's democratically-elected (and much beloved) leader and restored power to the Shah of Iran, a monarch. He was incompetent in myriad ways, and this led to revolution in 1979.
That's a very, very short summary that leaves out quite a bit, and I am in no way an expert on Iran. My point is that the United States directly overthrew the political leadership of Iran without just cause and continued to manipulate its affairs over the following decades.
Combined with our other brutal history in the Middle East, i.e. the illegal invasion of Iraq that led to the deaths of hundreds of thousands of innocent civilians, can you see why the situation here is extremely complicated and requires a hell of a lot of thoughtful practice?
Our own military leadership is aghast over Trump's actions. The option to assassinate Soleimani was reportedly presented to him as a way of illustrating the extreme end, making the other options more palatable. What an incredibly ridiculous and thoughtless approach.
Our military leadership knows they stepped in it big time here. Diplomatic and intelligence officials around the world are asking what the hell we were thinking. The situation is extremely dire. Bad. Really bad.
So, while West Point cadets are learning the tenets of Just War Theory and officials in the military, national security, diplomatic corps, and Congress are wondering just how badly we screwed things up here, Trump tweets out the following: 
We haven't done things right in a very long time, but now, not only have we completely neglected the supposed values of our country under Trump, the highest officials in our government don't even know what the goal is here. We are flying blind and without just cause. /thread
