Why did Connell (the author) make Rainsford an American and Zaroff a Cossack? Is there a political message to this story?

Connell was a veteran of WWI, an American veteran. Zaroff and Ivan are Russians.... cossacks, which was a group widely sought by the Soviet regime. This novel is more about the conflicts of men.... war, and human morality than it is about hunting. Rainsford and Zaroff provide the historical basis, which in turn, is political.