We need to study history well, and not trust people. If Ukraine is a separate state, then why do most of the population speak Russian? Where is the deception?
Not just that. The so called "Ukrainian language" actually evolved as a fringe dialect of the Russian language, heavily influenced by Polish and other West Slavic languages. In short, it is an artificial language.
It is possible to argue long. Considering that Kievan Rus was born earlier than Muscovy can be assumed that this is the different dialects of the same language. Both languages evolved in parallel.