In 2018, the Saudi journalist Jamal Khashoggi walked into the Saudi consulate in Istanbul to get documents that he needed to get married. Khashoggi never left. Khashoggi had written critical Washington Post pieces about Saudi Arabian Crown Prince Mohammad bin Salman and the Saudi intervention in Yemen. In apparent response, a group of operatives linked to MBS murdered and dismembered Khashoggi. MBS himself denied responsibility, but the CIA and UN investigators concluded that MBS had ordered Khashoggi’s assassination. There are all sorts of problems with the Saudi government, but the Khashoggi assassination is the incident that really turned public opinion against the royal family. Companies like the WWE who schedule events in Saudi Arabia have faced major backlash, and now Justin Bieber, who’s supposed to headline a show there next month, is facing a large-scale campaign to prevent him from taking part.

Right now, Bieber is scheduled to headline a show that’ll follow the Formula One Saudi Arabian Grand Prix in Jeddah December 5. The bill also includes Western performers like A$AP Rocky, Jason Derulo, David Guetta, and Tïesto. This past weekend, Hatice Cengiz, the woman who was engaged to marry Jamal Khashoggi, published an open letter to Bieber in The Washington Post. The piece singles out Bieber and asks him not to perform for MBS:

Do not sing for the murderers of my beloved Jamal. Please speak out and condemn his killer, Mohammed bin Salman. Your voice will be heard by millions.

If you refuse to be a pawn of MBS, your message will be loud and clear: I do not perform for dictators. I choose justice and freedom over money.

Beyond that open letter, there’s a whole campaign urging Bieber not to play the Saudi show. As TMZ reports, trucks with mobile billboards drove around outside the American Music Awards in Los Angeles last night, broadcasting messages like “It’s Not Too Late Now to Say Sorry. Don’t Sing for Saudi Arabia’s Dictator!” A plane also flew a banner saying “Why is Bieber singing for Saudi killers?”

Bieber hasn’t made any public comment about this campaign, and he hasn’t promoted his Saudi show at all.