The article highlights the behind-the-scenes policies of hybrid war of the Russian Socialist Federative Soviet Republic (RSFSR) against the Ukrainian State headed by Hetman Pavlo Skoropadskyi (April – December 1918). The author examines anti-Ukrainian activities of the Council of People’s Commissars of the RSFSR, the ruling Russian Communist Party (Bolsheviks), and the allied Russian parties of left and right socialist-revolution-aries and anarchists. These include Soviet Russia’s efforts to undermine social and political stability in Ukraine; organisational, armed, and financial assistance to anti-government insurgent units; guidance of the rebel movement; organisation of large-scale strikes and sabotage via secret agents as well as setting up arms caches and underground networks of revolutionary committees, etc. The article exposes secret aspects of subversive anti-Ukrainian activities of Bolshevik diplomacy in Ukraine, particularly of the Soviet consulate in Odesa, and its assistance to the anti-hetman movement with the acquiescence of German diplomats accredited to the Ukrainian State. Special attention is attached to the Soviet-Bolshevik policy of establishing secret military units of the underground socialist terrorist army in Ukraine and such steps of the Russian Soviet government as supporting and sponsoring mass rebel and terrorist movements and the direct organisation of acts of individual terror against Ukrainian public figures, including several attempts to assassinate Hetman Pavlo Skoropadskyi. The author notes that Ukrainian security services were aware of the structure, network, subversive activities, and organisation of attempted assassinations of the Ukrainian hetman. The article describes the preparation of the Soviet armed invasion of Ukraine and records the beginning of the military aggression in the autumn of 1918. Keywords: Bolshevik terror, RSFSR, Skoropadskyi, Ukrainian State, hybrid war.