My father in law joking about Hiroshima

I’m not from here so excuse my English.

Hello everyone, I’m originally from Japan, my husband and I have been married for 4 years. We met each other here in LA.

We usually visits my father in law’s house at least 3 times a week. They live couple blocks away from us and love seeing their grandson. We have dinners together and I can say we are very closed.

Recently my father in law is getting to my nerves. He often brings jokes about dropping bomb on Hiroshima knowing I’m from Japan. He made a song “We dropped the bomb on you” and likes humming the song in front of me.

We’ve been married for 4 years but my father in law wasn’t happy at all because they come from very religious Christian family, and they had high expectations for his son but my husband married me who didn’t go to church and wasn’t saved. (Now I’m saved and I go church with them) Once his grandson was born we got along again and moved on from the past. I think he got pretty comfortable.

I used to laugh and tried not to think deeply about it but I started feeling like it wasn’t cool. I don’t go up to someone and joke about 9.11. It’s not funny at all and it’s just soo rude... innocent people died.

I brought this subject to my husband and he said Japan attacked first and they deserved it so I shouldn’t even get offended. I don’t really care who attacked first or not, I don’t care about history, my point is he shouldn’t make fun of it because so many people died. It’s very sensitive subject especially I’m very educated about it.

I just don’t get why he does this. I wish it was easy to just tell him that I don’t wanna hear about it.