idk, there hasn't been any effective war resistance in the US in my lifetime. I doubt we'd have any more luck than the Russian anti-war movement did when the Ukraine war started. Plus, protesting a cop murdering someone is nominally protected under the first amendment. Any serious protest of a war is sedition, and the way immigration laws have been re-written and interpreted they could very easily start stripping citizenship from people deemed insufficiently loyal. I don't know if they would, but the US is certainly set up for extreme repression of an anti-war movement that showed any signs of gaining teeth.