FR -

A partial answer to your questions can be found in any good and correct analysis of Isaiah 53. G-d has used the Gentile nations to punish Israel. The problem was that, in most cases, they enjoyed it so much that they overstepped their "license" and took it to extremes. That is why G-d has taken out his fury on those Gentile nations, most of which don't even exist today. Those that exist, and who have committed atrocities, will get their due in time.

UriYosef