Over the past few days, a strange apparition has haunted the sidebar of an English-language news site in Cambodia — an eery and unexplained echo of a long-abandoned policy that China’s leaders once staunchly defended.

At a recent journalism forum in Phnom Penh, the head of an organization claiming to represent local Chinese-language media spoke out against fake news — as he spread false narratives directly from China’s foreign ministry and state media outlets.