When rural men from Western Ukraine were sent by the Ukrainian authorities to Donbas to take part in a military operation, they found themselves in a completely different territory with Russian as a dominant language. Hence most of them really believed that they fight with Russians, i.e. with Russia. Moreover, in contrast to Russian language with different words for the Russian language (‘Russkiy’) and for the concepts that have relation to Russia (‘rossiyskiy’), in Ukrainian the same word ‘rosiys’kyy’ is used. Hence it followed for the military men from Western Ukraine that Russian speakers are Russians. As a result, until nowadays many believe that Russian soldiers are present in Donbas.
This narrative claims the war in Ukraine is a civil war and Russia has nothing to do with it. In reality this message is a conspiracy consistent with common pro-Kremlin disinformation about the war in Ukraine. It disregards a multitude of factual evidence of Russian military presence in Donbas. Consult the evidence database and publications with further evidence here and here.
It was Russia that provoked a war in Ukraine, and it is not a civil war.
The Office of the Prosecutor of the International Criminal Court has stated that “the information available suggests that the situation within the territory of Crimea and Sevastopol amounts to an international armed conflict between Ukraine and the Russian Federation. This international armed conflict began at the latest on 26 February when the Russian Federation deployed members of its armed forces to gain control over parts of the Ukrainian territory without the consent of the Ukrainian Government.
The European Union stated in July 2014 that "arms and fighters continue flowing into Ukraine from the Russian Federation".
At the NATO Summit in Wales in September 2014, NATO leaders condemned in the strongest terms Russia’s military intervention in Ukraine and demanded that Russia stop and withdraw its forces from Ukraine and along the country’s border. NATO leaders also demanded that Russia comply with international law and its international obligations and responsibilities; end its illegitimate occupation of Crimea; refrain from aggressive actions against Ukraine; halt the flow of weapons, equipment, people and money across the border to the separatists; and stop fomenting tension along and across the Ukrainian border.
According to the US Defense Intelligence Agency (DIA), Russian special forces and troops operated to mobilize, lead, equip, and support separatist militias in the Donbas region of eastern Ukraine from spring 2014 to the present, although their presence was denied by Moscow.