Outspoken Chinese artist Ai Weiwei has joined the ranks of other dissidents who have irked the government. He has simply gone missing.

Police detained Ai at Beijing Airport on Sunday, as he was en route to Hong Kong. His Beijing studio was also raided on the same day. He has not been heard of since, and there has been no comment from the authorities.

The 53-year-old’s disappearance comes amid heightened tensions in China with the authorities jumpy about the (albeit remote) possibility of any Middle East style protests spreading to the mainland. Several rights lawyers, activists and bloggers have either been charged or disappeared since February.

The western media is sounding a forbidding note about this latest development. While Ai has frequently wrangled with the authorities because of his efforts to push human rights — he’s been punched by provincial police, held under house arrest, and prevented from leaving the country — this is the first time he has been missing for so long. This is Time magazine’s pessimistic take on the situation.

His prominence owes itself to the fact that as a leading artist, he would be globally recognized even without his activism. And for so long that had also been a shield. By holding him, the Chinese authorities are reminding the nation that no challenger to the rule of the Communist Party should feel safe.