I used to constantly have "the Russia problem" on eBay. It used to piss me off before... when I would say "USA ONLY!" in big bold letters and they would still bid!
On my eBay auctions, I choose which countries I ship to...
But... also... to prevent Russia buyers (with USA addresses) from bidding, I have these settings set in my eBay Account Settings:
I like all of the ones I have selected... but the real important one is:
"Block Buyers who has a primary shipping address in a location I don't ship to."
Ever since I set up these settings, I have not had any issue with Russian buyers being able to bid on my auctions.
On my eBay auctions, I choose which countries I ship to...
But... also... to prevent Russia buyers (with USA addresses) from bidding, I have these settings set in my eBay Account Settings:

I like all of the ones I have selected... but the real important one is:
"Block Buyers who has a primary shipping address in a location I don't ship to."
Ever since I set up these settings, I have not had any issue with Russian buyers being able to bid on my auctions.