“There would be no missiles launched into Moscow if Russia were not launching missiles into Ukrainian cities. Why is this so hard to understand?”
Because Ukrainian cities are not the capital of the United States.
Think about it, it’s not complicated.
Your response does not address the fact that Ukraine sending missiles to Moscow is in response to Russia sending missiles to Ukrainian cities. If Russia would stop bombing Ukrainian cities then Ukraine would stop bombing Moscow. It is not that hard. What you seem to want is the ability of Russia to bomb Ukraine without any response. That is not how it works.