Here's the fun part. The embassy is Russian.
Apparently the logic behind their anger is that it was Soviet Union who caused the bombings by silently agreeing to it when they had a chance to stop them. Americans however did nothing wrong, they merely showed Japanese how caught up in the war they were and helped them to see the light. This is clearly not a widely shared opinion, but it just goes on to show how really contrived the subjective part of the issue is.