A comment on warning shots: you're damned if you do, and damned if you don't, but not all damnation carries the same weight.
If self defense training, they tell us never to fire a warning shot - for almost purely legal reasons. Third parties and their points of view complicate everything when you're supposed to be concentrating on protecting your own life in an ethical fashion. In military policy, a "warning shot" - also known as proportionate response - is either way too much or way too little, depending who's bleating about it.
But the point is the effect on the enemy's future behavior. And eventual success refutes all objections... eventually. Also, international law is a joke so we can safely ignore that.
So ignore the complainers on both sides. What matters is the end result, and we don't know yet what that will turn out to be.
But we do know that Odammit's approach to foreign policy didn't work worth shit. Hindsight is the verdict of history, and it has the final word.
By the way, Odammit took flack in certain circles for targeted drone killings, and Mosul, and... whatever. My only complaint is he didn't manage to keep the world safe for freedom. Nothing fails like failure.
The Donald has inherited a mess in the Middle East and another in Korea, and yet another in US health care. He gets to blame his predecessor for a year, two max. After that whatever the situation is, he owns it.