Madonna, the pop superstar, is unable to escape controversy with her MDNA tour. This series of concerts around the globe has attracted significant scrutiny and bad press. Today, she received a violent threat regarding her scheduled concert in St. Petersburg, Russia.

The U.S. Embassy recommends that citizens “remain vigilant regarding their personal security,” according to TMZ.

Few specific details about the physical threat have been provided, but they may be retaliation for any number of controversial images she has used in her previous concerts. For example, Madonna emblazoned swastikas on a picture of a right-wing French politician. She has included sacred Christian icons into her show, as well, drawing anger from Catholic groups.