Chicago and its police union have escalated their battle over COVID-19 vaccines, with the city filing a formal complaint against the Fraternal Order of Police for threatening an illegal strike. The city had mandated its employees to declare their vaccination status by Friday, but said it would allow for a twice-weekly testing option for those who chose not to get the shot. “As Chicago’s mayor, I cannot and will not stand idly by while the rhetoric of conspiracy theorists threatens the health and safety of Chicago’s residents and first responders,” Mayor Lori Lightfoot said in a statement, per The New York Times. “President [John] Catanzara has time and again deliberately misled our police officers by lying about the requirements of the policy and falsely claiming that there will be no repercussions if officers are insubordinate and refuse to follow a city and department directive or order.”

The police union denied it was encouraging a strike, but in a series of videos this week, Catanzara had urged his members to forgo the requirement and face whatever consequences were presented. “Whatever happens because of the manpower issue, that falls at the mayor’s doorstep,” Catanzara said in a video Tuesday.