You want my thought process?
"Hm, I need a reason why everything outside is dead"
"Nukes. Nukes are good."
"Who has nukes?"
"USA. Russia. North Korea. Uh... I have no idea who else."
"Where is my character? Ugh. Why do I need to waste thoughts on deciding where he is. Hm. I might want to make this more than just a short story, so I should pick a country I know something about, to make it easier for myself. Germany? France? Great Britain?"
"I just had Great Britain. Meh. Also, if his country has been nuked, he wouldn't still be alive."
"Should be an allied country that's nuked then, far away enough."
"USA. Let's nuke the USA."
"That only leaves Russia and North Korea, I am too lazy to look up who else has nukes."
"Nobody takes North Korea seriously."
"Russia it is."
That is the exact the same process as I was describing it but with one huge difference. That difference is in using Russia just for the story purposes and nothing deeper than that. You already told me that in your first reply, I saw that. I already told you my general opinion about “using it just for the story purposes” in my very first comment. But, in your particular case, by the way you conducted yourself in your replies and from the “tone” of your replies it made me think, made me believe that you were using it just for the story purposes.