The Whites

The National Government (Also referred to as the Imperialists, the Whites, and the Imperial Army) were the main fighting force behind that Ukrainian oppression, they hoped to re-establish a Russian authority in Ukraine and use its natural resources to continue the war effort against the Bolsheviks. While they did manage to reconvene authority for a little bit, the Bolshevik forces were easily able to wipe out all of their gains in less than a year. 

"Denikin's [Commander in chief of the Russian Imperial Army] advance in the Ukraine was most spectacular. He took Poltava on July 31, Odesa on August 23, and Kyiv on August 31."  - Peter Kenez