Politically... if we don’t give it to him we’ll be blamed for ALL the failures from his weak leadership in the world.
And we would be cementing the world’s view of American futility in the world.
Though he is the one responsible for it- we get the blame.
Legally, he needs congressional authorization first.
Though the urgency to act to defend civilians may give him cover under existing law. There may be some law or treaty wording about acting in a case like this.
“On March 23, 1999, the day before President Clinton approved
the use of force in Kosovo, the Senate adopted a resolution authorizing
“air operations and missile strikes” in cooperation with NATO
against Yugoslavia.20 On March 24, the same day the President
acted, the House of Representatives adopted a resolution supporting
U.S. armed forces “engaged in military operations against the Federal
Republic of Yugoslavia.”21”
You're probably right. But we should insist before he does it that he seek the proper approval. When he does it without the proper approval, the House should pass a resolution reprimanding him for failing to obide by the law. That keeps the precedent and puts him on notice without a full impeachment that would backfire and fail.