A guerilla assumes that Russia occupies Ukraine. I think this is improbable, I do not think that Russia want to deal with guerilla warfare and probable terrorist attacks coming from extremists from there. The east part of Ukraine in Donbass, recognized as independent by them, is precisely the part of Ukraine with more ethnical Russians that is against the Ukrainian government and were de facto independent and more pro-russian since years ago during Ukrainian civil war. From there a guerilla would be improbable. This attacks probably are more to send a message against NATO expansion there and to defend Donbass independence, not an invasion for occupation.