ok i think that two extraction teams were sent to verruct. one was the team lead by tank the other was hit by a 115 meteor and crashed. the meteor created zombies that attacked the crash survivers. tanks team got there but only found zombies and at some point the nazis came back to verruct and captured the only person they saw which was tank. so in my theory it makes pefect sense that natch der untoten takes place in gremany at the same time as verruct. and for SNN i have no idea where that might be my guess is japan tho and thats why rictofen has the line on kino "they must have got this from japan" when you find the first meteor piece.