The just-war theory also stipulates that a rightful intervention must have a reasonable chance of success. That, too, seems unlikely here given how the response played out last year, according to Helen Frowe, a philosopher at Stockholm University who specializes in the ethics of war and foreign intervention. I reached out to Frowe because she’s taken a strong stance on philosophy’s famous Trolley Problem: She argues that if you can flip a switch and redirect a runaway trolley so that instead of killing five people it will kill only one, you’re not just permitted but actually morally required to do so. Many would argue that the United States had a moral requirement, then, to risk some Syrian and American lives earlier in the conflict if there was a chance of stopping the massive loss of life that has occurred in the intervening years. But what does that mean today? I asked Frowe if she thinks Trump striking Syria now would be akin to flipping that switch.

“I think that when you know you’re able to save a significant number of lives by causing significantly less harm, you’re required to do that. The problem is, I don’t think a strike now is going to save any lives,” she said. “The last time Trump did that, it clearly didn’t prevent the regime from using chemical weapons.” Similar strike options are reportedly under consideration now.