"Green men" (also called "Polite men") were in Crimea and there is no war in Crimea now. And there is a question: why ukrainian army doesn't fight in Crimea? Maybe because there is REALLY russian army in Crimea?
And there is NO russian army in Donbass. So ukrainian army "defends against russian army" in Donbass (really not).
"Civil war" is a
war between organized groups within the same
state.
There were some exchanges of prisoners of war. Do you know the citizenship of overwhelming majority of prisoners on both sides? Yes, they were Ukrainians on both sides.
Do you remember the Civil war in Spain in 1936-39? Were Nazi Germany and USSR involved and supporting both fighting sides? Yes. Was it called a war between Germany and USSR? No, it was Spain civil war.
Any civil war had foreign countries involved in. Russia supports one side, West supports the other side. Anyway its a civil war because the main fighters have one citizenship: Ukrainian.