So if you were beating the crap out of me with a spade and I punched you back then I am responsible for punching you in self defense?No.
When you pull the trigger, you decide to pull the trigger, you are responsible.
Following your excuse, not your logic, Ukraine is responsible for the entire chain of events, for whoever wants to say so.
I wouldn't have done it if you hadn't hit me with that spade.
Victim blaming seems to be very popular with some people.