US Confronted with a similar situation there would be no symmetrical attrition. Russia would never have been allowed to enter the land let alone fully invade and its industries and infrastructure would be gutted. That’s why Russia only picks on small military targets so they can be the big bad bully. The only thing we can learn here is how foolish and immoral the Russians are under Putin. Also, next level robotics and AI will change everything soon so better work the diplomatic channels harder. Avoid war. War is obsolete.