It's certainly a work in progress but it seems that they have been testing at least marginally functional versions of the missile complete with nuclear powered

It's certainly a work in progress but it seems that they have been testing at least marginally functional versions of the missile complete with nuclear powered propulsion[1]. [1]https://www.thedrive.com/the-war-zone/18948/u-s-has-been-secretly-watching-russias-nuclear-powered-cruise-missiles-crash-and-burn https://www.thedrive.com/the-war-zone/18948/u-s-has-been-sec...