Visitors descended on Washington’s National Zoo on Friday to witness the cheery unveiling of two pandas on loan from China. Fans posted photos and videos to social media, as did the zoo under the hashtag #DCPandas.

But in China, the government has sent a chilling message to panda fans to watch what they say online. Some online influencers have been arrested or questioned over what the authorities called “rumors” and “radical fan culture.”

The police have targeted people who have advocated for animal welfare or criticized overseas exchanges like the one that brought pandas to Washington. But state media has also published warnings about broader panda fandom. The moves come amid Chinese leader Xi Jinping’s crackdown on internet fan culture.

China has millions of panda fans, many of whom have taken up the cause of animal welfare in a country where aggressive breeding tactics have injured bears and led to cubs being prematurely separated from their mothers. For years, the authorities tolerated their online activism and criticism, which targeted both Chinese and foreign zoos.

No more. Last month, the police in Sichuan Province said they had arrested 12 people for smearing panda experts, inciting violence and spreading false information about pandas, including two that used to live at the National Zoo.

The authorities have accused panda influencers of harassing staff at Chinese breeding centers and growing rich from livestream donations. The police claim to have uncovered panda-focused “radical animal protection gangs” in three provinces, according to state media.