“Of course the U.S. wants Russia to have a weaker military. So does everyone else in Europe right now. Why is this so hard to understand?”
Because he says it out loud. Bad idea to tell a paranoid megalomaniac that you really are out to get him. It makes it harder to get him.
Also because he doesn’t do the one thing that can meaningfully weaken him, which is to send American oil and natural gas to Europe. Green New Deal Uber Alles!