Yeah, we know his latest cavalcade of stupid shit marks an attack on the rules based order. We know it basically puts the US in the position of agreeing with Putin's world view. We also know none of it will come to pass.
So what should the response from the left be? Ignore it unless asked. If asked, I respectfully submit they should respond with something along the following lines.
Felonious wants to send your kids to die in Canada, Greenland, Mexico and Panama to line the pockets of foreign robber barons and carpet baggers who back him. They and the MIC are the only ones who will benefit from the wars he wants to start. To add insult to injury, he will end up making those refugees lining up at our Southern Border legal residents with a path to citizenship.
I know, I know. That's some pretty stupid sounding shit, but that's kind of the point.
Fight fire with fire... and do so with a straight face.