What's wrong with helping a country defend itself from invasion by imperial warmongers?

And to be clear, yes, I am calling Russia imperial warmongers. They have been actively invading neighboring countries for decades to expand themselves. And what is an empire if not a nation built on the conquest of other countries?

Supporting Ukraine is the only U.S. military action since WW2 that I can truly support. Even our action in response to 9/11 was fucked up.