Jeffrey Hall, a professor at Kanda University of International Studies, pointed out that #NoBarbenheimer was trending on Japanese Twitter on Sunday. Users were especially critical of memes that combined photos of Barbie with images of the atomic bomb and other stills from Oppenheimer.

The official Barbie Twitter account has interacted with and promoted some of those memes.

Warner Bros. Japan said in a statement Monday that the Barbenheimer movement was fan-driven, and it finds it “extremely regrettable” that the American account for the movie engaged with it. It said it reached out to the U.S. studio and asked that it “take appropriate action” on the issue.

Oppenheimer does not yet have a release date in Japan. Some have questioned whether it will get a wide release there given its subject matter, though Japan has a history of engaging with films about World War II, from both domestic and foreign filmmakers.