It was referred to as the Ukraine when it was a part of the former Soviet Union. Since they were split apart and Ukraine became a country it should properly be called Ukraine without the definite article.
The name Ukraine, which first appeared in the historical chronicles in 1187, has been common in the English language for almost 350 years. In the earliest years it appeared without the definite article 'the' but in this century the definite article increasingly preceded the name Ukraine. ... many Ukrainian immigrant scholars, due to their imperfect knowledge of English, used the form 'the Ukraine' in their books thus helping to perpetuate this usage.
Ukrainians who understood why Soviets were using the article 'the' complained. In Russian, obviously, the word 'Ukraina' has no article. Since the Soviet Union broke apart, Ukrainians have been pushing very hard to have the article 'the' removed from the English translation, so as to be linguistically correct, ie to show that Ukraine is a separate, independent country, not part of another country.