When I visited the Arizona Memorial at Pearl Harbor, there was a large group of Japanese tourists, probably in their 20s, on the same boat going out to the memorial. When we out there, they all started laughing and taking pictures of each other and having a great time. I wasn't the only person that was offended by their actions, but they didn't appear to speak any English, so it seemed pointless to say anything to them. So, when we got back from the memorial, I walked past them and said very loudly, "Remember Hiroshima."
I have no idea if they understood me, but it made me feel better.