It all goes back to the Kievan Rus.
The territory of modern Ukraine has been inhabited since 32,000 BC. During the Middle Ages, the area was a key centre of East Slavic culture, with the powerful state of Kievan Rus'
Now whilst some Ukranians might be of the belief that they are different from Russia, (others may not) the name Russia actually is derived from "Rus".
The name Russia is derived from Rus', a medieval state populated mostly by the East Slavs
And just like modern day Russians are derived from Slavs, Ukranians are also Slavs.
The territory of modern Ukraine has been inhabited since 32,000 BC. During the Middle Ages, the area was a key centre of East Slavic culture
Both Ukranians and Russians may actually be surprised to learn, that the word Rus, derives neither from Russia nor Ukraine, but in fact from Scandinavia.
Swedish Rus people
Swedish Rus people
The name Rus itself comes from the early medieval Rus' people, Swedish merchants and warriors who relocated from across the Baltic Sea and founded a state centered on Novgorod that later became Kievan Rus.
However there has been so much political damage done to the area, from the Goths to the Huns, and all those different empires splitting areas up and dividing people. From the Roman, to the Holy Roman, et cetera.
People dont know who they are anymore, and when they get conquered, some groups of people manage to keep their original identity and loyalties, whilst others simply assume themselves as being citizens of the new empire.
Now the real confusion is caused mostly by the Holy Roman Empire.
The Rus kingdom got divided up by the Byzantines. And this little area, neither Scandinavian, nor Russian, but assuming both a Scandinavian and Russian name, appeared, called "Kievan Rus". A nice little bit of stolen land for the Byzantines.
The Russians however rescued the Rus empire and it turned in to the Russian empire.
But by this time, many people had forged new identities.
The medieval state of Rus' arose in the 9th century. In 988 it adopted Orthodox Christianity from the Byzantine Empire, beginning the synthesis of Byzantine and Slavic cultures that defined Russian culture for the next millennium. Rus' ultimately disintegrated into a number of smaller states, until it was finally reunified by the Grand Duchy of Moscow in the 15th century. By the 18th century, the nation had greatly expanded through conquest, annexation, and exploration to become the Russian Empire,
In fact, the downfall of Rus can probably quite accurately be pinpointed to have began in 867ad.
In 867 the Patriarch announced that the Rus' had accepted a bishop, and in 874 he speaks of an "Archbishop of the Rus'."
But i think beneath the political and religious arguments, there may also be racial undertones.
I do not think that Slavs are quite the same as Scandinavians, and both Aryans and Slavs for at least 15,000 years now have both shared the mainland of europe (and fought over it) and had huge influence in the history of Russia.
This has probably been an issue that dates back to the creation of the ahrensburg culture during the younger dryas when Northern peoples migrated south
The Ahrensburg culture or Ahrensburgian (c. 12,900 to 11,700 BP1) was a late Upper Paleolithic nomadic hunter culture (or technocomplex) in north-central Europe during the Younger Dryas, the last spell of cold at the end of the Weichsel glaciation resulting in deforestation and the formation of a tundra with bushy arctic white birch and rowan. The most important prey was the wild reindeer. The earliest definite finds of arrow and bow date to this culture, though these weapons might have been invented earlier. The Ahrensburgian was preceded by the Hamburg and Federmesser cultures and superseded by the Maglemosian and Swiderian cultures. Ahrensburgian finds were made in southern and western Scandinavia, the North German plain and western Poland.
But the clash of cultures and ethnicity is an issue that will never be resolved, until everyone just assumes themselves human.