Speaking for Korea at the end of the war there was little understanding of what a nuclear weapon was and because it was under japanese control there were few that were even aware of it. Even for those who might've heard of the bombings the big news was that japan had surrendered. Internal issues, e.g. political, reunification, were front of mind in the years prior to the korean war.

Today the attitude would be that it's a tragedy but one of many during the war. If the topic comes up there'd be sympathy for the civilians who died but little for the state of japan because after all they'd started the war.

In the west we seem to see the bombings as one of the landmark events of the war and it always seems to draw hot debate, like it did recently when Kerry visited the bombed cities. I'd speculate that nuclear weapons became embedded into the collective psyche as weapons of armaggedon through the experience of the cold war but in korea the main concerns were geared more towards north korea and simply survival so the understanding of the cold war is more local.

Even when north korea did its nuclear tests it seemed that there was more concern in the west than in korea.